Of Gastric Carcinoma (JCGC) [16].Evaluation of Monoclonal Antibodies for MUCCells and culture conditions. Human gastric cancer cell lines (SNU-16 and NCI-N87) and pancreatic cancer cell lines (PANC1 and CAPAN1) were purchased from the American Type Culture Collection (Manassas, VA). Both gastric cancer cells were maintained in RPMI-1640 (Sigma-Aldrich, St Louis, MO); PANC1 cells were maintained in DMEM (Sigma-Aldrich);MUC4 and MUC1 Expression in Early Gastric CancersMUC4 and MUC1 Expression in Early Gastric CancersFigure 2. Expression patterns of MUC4/8G7, MUC4/1G8 
and MUC1/DF3 in each histological type of gastric carcinoma. Hematoxylineosin (HE) (A), MUC4/8G7 (B), MUC4/1G8 (C) and MUC1/DF3 (D) in papillary adenocarcinoma (pap). HE (E), MUC4/8G7 (F), MUC4/1G8 (G) and MUC1/ DF3 (H) in well differentiated tubular adenocarcinoma (tub1). HE (I), MUC4/8G7 (J), MUC4/1G8 (K) and MUC1/DF3 (L) in moderately differentiated tubular adenocarcinoma (tub2). HE (M), MUC4/8G7 (N), MUC4/1G8 (O) and MUC1/DF3 (P) in mucinous carcinomas (muc). HE (Q), MUC4/8G7 (R), MUC4/1G8 (S) and MUC1/DF3 (T) in solid type poorly differentiated adenocarcinoma (por1). HE (U), MUC4/8G7 (V), MUC4/1G8 (W) and MUC1/DF3 (X) in non-solid type poorly differentiated adenocarcinoma (por2). HE (Y), MUC4/8G7 (Z), MUC4/1G8 (a) and MUC1/DF3 (b) in signet-ring cell carcinoma (sig). MUC4/8G7 was expressed in the cytoplasm of pap (B), tub1 (F) and tub2 (J), but not in muc (N), por1 (R), por2 (V) nor sig (Z). MUC4/1G8 was expressed mainly at the cell apexes of pap (C), tub1 (G) and tub2 (K), but not in muc (O), por1 (S) nor por2 (W). MUC4/1G8 expression was seen in the intracytoplasmic mucin substance of sig (a). MUC1/DF3 was expressed mainly at the cell apexes tub2 (L), but not expressed in the cases shown in this figure (D, H, P, T, X and b). Original magnification 6200 (A , M ), 6400 (I , U ). doi:10.1371/journal.pone.0049251.gCapan1 cells were maintained in 15755315 DMEM/F-12 (Sigma-Aldrich). 
All media were supplemented with 10 fetal bovine serum (GIBCO, Breda, The Netherlands) and 100 U/mL penicillin/ 100 mg/mL streptomycin (Sigma-Aldrich). All cells were incubated in 5 CO2 at 37uC and maintained at sub-confluent levels. RNA extraction and RT-PCR. Total RNA was extracted from the cells using the RNeasy mini kit (Qiagen, Hilden, Germany) and quantified by NanoDrop ND-1000 spectrophotometer. The obtained mRNA (2ug) was reverse transcribed to cDNA with the High Capacity RNA to cDNA kit (Applied Biosystems, Foster City, CA). The following primers were designed for the subsequent PCR: MUC4, 59- TGGGACGATGCTGACTTCTC-39, 59-CCCCGTTGTTTGTCATCTTTC-39; ACTB, 59-CTCTTCCAGCCTTCCTTCCTG-39, 59-GAAGCATTTGCGGTGGACGAT-39. PCR was performed with the AmpliTaq Gold Fast PCR Master Mix (Applied Biosystems) following the manufacturer’s protocol. Protein extraction and western blotting. Total cell lysates were prepared using RIPA buffer containing protease inhibitor cocktail (Nacalai Tesque, Kyoto, Japan). The protein concentration was measured by the BCA assay (Thermo Scientific, Rockford, IL). An equal amount of protein lysate was resolved on 2 agarose gel containing SDS and passively transferred onto PVDF membrane overnight at room temperature. EAI045 cost Membraneswere DOPS site blocked with 1 skim milk/PBST over 2 hours and subjected to the standard immunodetection procedure using specific primary antibodies. The primary antibodies are as follows: anti-human MUC4 MAb 8G7 (1:1000, generated by Dr. Surinder K. Batra, University o.Of Gastric Carcinoma (JCGC) [16].Evaluation of Monoclonal Antibodies for MUCCells and culture conditions. Human gastric cancer cell lines (SNU-16 and NCI-N87) and pancreatic cancer cell lines (PANC1 and CAPAN1) were purchased from the American Type Culture Collection (Manassas, VA). Both gastric cancer cells were maintained in RPMI-1640 (Sigma-Aldrich, St Louis, MO); PANC1 cells were maintained in DMEM (Sigma-Aldrich);MUC4 and MUC1 Expression in Early Gastric CancersMUC4 and MUC1 Expression in Early Gastric CancersFigure 2. Expression patterns of MUC4/8G7, MUC4/1G8 and MUC1/DF3 in each histological type of gastric carcinoma. Hematoxylineosin (HE) (A), MUC4/8G7 (B), MUC4/1G8 (C) and MUC1/DF3 (D) in papillary adenocarcinoma (pap). HE (E), MUC4/8G7 (F), MUC4/1G8 (G) and MUC1/ DF3 (H) in well differentiated tubular adenocarcinoma (tub1). HE (I), MUC4/8G7 (J), MUC4/1G8 (K) and MUC1/DF3 (L) in moderately differentiated tubular adenocarcinoma (tub2). HE (M), MUC4/8G7 (N), MUC4/1G8 (O) and MUC1/DF3 (P) in mucinous carcinomas (muc). HE (Q), MUC4/8G7 (R), MUC4/1G8 (S) and MUC1/DF3 (T) in solid type poorly differentiated adenocarcinoma (por1). HE (U), MUC4/8G7 (V), MUC4/1G8 (W) and MUC1/DF3 (X) in non-solid type poorly differentiated adenocarcinoma (por2). HE (Y), MUC4/8G7 (Z), MUC4/1G8 (a) and MUC1/DF3 (b) in signet-ring cell carcinoma (sig). MUC4/8G7 was expressed in the cytoplasm of pap (B), tub1 (F) and tub2 (J), but not in muc (N), por1 (R), por2 (V) nor sig (Z). MUC4/1G8 was expressed mainly at the cell apexes of pap (C), tub1 (G) and tub2 (K), but not in muc (O), por1 (S) nor por2 (W). MUC4/1G8 expression was seen in the intracytoplasmic mucin substance of sig (a). MUC1/DF3 was expressed mainly at the cell apexes tub2 (L), but not expressed in the cases shown in this figure (D, H, P, T, X and b). Original magnification 6200 (A , M ), 6400 (I , U ). doi:10.1371/journal.pone.0049251.gCapan1 cells were maintained in 15755315 DMEM/F-12 (Sigma-Aldrich). All media were supplemented with 10 fetal bovine serum (GIBCO, Breda, The Netherlands) and 100 U/mL penicillin/ 100 mg/mL streptomycin (Sigma-Aldrich). All cells were incubated in 5 CO2 at 37uC and maintained at sub-confluent levels. RNA extraction and RT-PCR. Total RNA was extracted from the cells using the RNeasy mini kit (Qiagen, Hilden, Germany) and quantified by NanoDrop ND-1000 spectrophotometer. The obtained mRNA (2ug) was reverse transcribed to cDNA with the High Capacity RNA to cDNA kit (Applied Biosystems, Foster City, CA). The following primers were designed for the subsequent PCR: MUC4, 59- TGGGACGATGCTGACTTCTC-39, 59-CCCCGTTGTTTGTCATCTTTC-39; ACTB, 59-CTCTTCCAGCCTTCCTTCCTG-39, 59-GAAGCATTTGCGGTGGACGAT-39. PCR was performed with the AmpliTaq Gold Fast PCR Master Mix (Applied Biosystems) following the manufacturer’s protocol. Protein extraction and western blotting. Total cell lysates were prepared using RIPA buffer containing protease inhibitor cocktail (Nacalai Tesque, Kyoto, Japan). The protein concentration was measured by the BCA assay (Thermo Scientific, Rockford, IL). An equal amount of protein lysate was resolved on 2 agarose gel containing SDS and passively transferred onto PVDF membrane overnight at room temperature. Membraneswere blocked with 1 skim milk/PBST over 2 hours and subjected to the standard immunodetection procedure using specific primary antibodies. The primary antibodies are as follows: anti-human MUC4 MAb 8G7 (1:1000, generated by Dr. Surinder K. Batra, University o.