SMAD3 and colorectal carcinoma: We studied 18 genes known to be important in CRC susceptibility (APC, AXIN2, BMP4, BMPR1A, CHEK2, MLH1, MLH3, MSH2, MSH3, MSH6, MUTYH, PMS1, PTEN, SMAD4, STK11, STK11IP, TGFBR2, and TP53) and 18 genes suspected to play a role in CRC susceptibility (AXIN1, BLM, BUB1, CDH1, CDKN1B, CDKN2A, CTNNB1, FLCN, GALNT12, NUDT1, OGG1, PALB2, REQL5, SMAD1, SMAD2, SMAD3, TGFB1, and TGFBR1).