The frequency of expression and localization of cripto-1 (CR-1), amphiregulin (AR), transforming growth factor alpha (TGFα), epidermal growth factor receptor (EGFR) and erbB-2 were examined by immunohistochemistry in 45 carcinomas and adjacent non-involved normal colon mucosa. Thirty (66.7%), 24 (53.3%), 23 (51.1%), 23 (51.1%) and 13 (28.9%) of the 45 carcinomas showed positive staining for CR-1, AR, TGFα, EGFR and erbB-2, respectively, whereas 7 (15.5%), 17 (37.7%), 15 (33.3%), 20 (44.4%) and 0 (0%) of the corresponding non-involved normal mucosa specimens were reactive. Among 13 carcinomas with lymph node involvement, 10 (76.9%), 8 (61.5%), 10 (76.9%), 8 (61.5%) and 7 (53.8%) exhibited positive staining for CR-1, AR, TGF-α, EGFR and erbB-2, respectively. There was a statistically significant association between the frequency of either TGFα (P<0.05) or erbB-2 (P<0.05) expression and lymph node metastasis. In addition, a signficantly higher frequency of positive staining for TGFα was observedin Dukes' grade C carcinomas (P<0.05). Finally, significant trends for coexpression of EGFR and either TGFα (P<0.01) or AR (P<0.05) were detected in carcinomas. These data suggest that AR and TGFα may play an important role in the development of colorectal carcinomas through an autocrine mechanism involving EGFR, and demonstrate that TGFα and erbB-2 may be more reliable indicators of metastasis or prognosis than CR-1, AR or EGFR in human colon cancers.