(A) SW1116 cell number was assessed following growth in the absence or presence of 10−7 M gastrin for periods of 3, 5, 7, and 10 days. Cell counts are expressed as values normalized to those of untreated cells (upper panel). * P<0.05 (n=3). Expression of AE2 and cyclin D1 was detected by immunoblot (lower panel). (B) Effect of 10 days’ treatment of SW1116 cells with 10−7M gastrin was assessed by clonogenic assay using crystal violet staining (upper panel, left) and phase contrast microscopy (upper panel, right). Number of clones per dish after 10 days in the absence or presence of 10−7M gastrin (lower panel), * P<0.05 (n=3). (C) Immunoblot analysis of AE2, EGR1, and P16 in SW1116 cells treated without or with 10−7M gastrin for 24 hrs (left panel). Immunoblot analysis of ERK and P-ERK in SW1116 cells treated with 100 μM H2O2 in the absence or presence of 10−7M gastrin for 24 hrs (right panel). (D) Cell growth of SW1116 cells treated with ERK inhibitors (30 μM U0126 or 50 μM PD98059). Inset, immunoblot analysis of P-ERK. * P<0.05 (n=3). (E) Immunoblot analysis of AE2 in SW1116 cells treated with 0.25 or 0.5 mM 5-Fluorouracil (5-Fu) for 24 hrs. (F) Immunoblot detection of AE2 expression in SW1116 cells treated with 10−7M gastrin in the absence or presence of the cholecystokinin B receptor (CCKBR) antagonist proglumide (10−4 M). (G) Immunoblot detection of CCKBR expression in colon cancer cell lines.