Abstract. In this study, the putative laminin receptor function of the a6ß4 integrin was assessed . For this purpose, we used a human cell line, referred to as clone A, that was derived from a highly invasive, colon adenocarcinoma . This cell line, which expresses the a6ß4 integrin, adheres to the ES and not to the PI fragment of laminin . The adhesion of clone A cells to laminin is extremely rapid with half-maximal adhesion observed at 5 min after plating . Adhesion to laminin is blocked by GoH3, an a6 specific antibody (60% inhibition), as well as by A9, a 04 specific antibody (30% inhibition) . Most importantly, we demonstrate that a6ß4 binds specifically to laminin-

SILC is feasible when performed on select patients by surgeons with extensive laparoscopic experience. Outcomes were similar to MLC, except for a reduction in peak pain score on the first postoperative day. Prospective randomized trials should be performed before incorporation of this technology into routine surgical care.

The Mac-2 lectin (carbohydrate binding protein 35) is a soluble, 32-to 35-kDa phosphoprotein that binds galactose-containing glycoconjugates. We report here that the colonic epithelium is a major site of Mac-2 expression in vivo based on immunohistochemistry of human tissue specimens. In this epithelium, proliferating cells at the base of the crypts do not express Mac-2 but its expression increases with differentiation along the crypt-to-surface axis. Mac-2 expression is concentrated in the nuclei of these differentiated epithelial cells.The progression from normal mucosa to adenoma to carcinoma is associated with significant changes in Mac-2 nuclear localization and expression. In all adenomas (9/9) and carcinomas (13/13) examined, Mac-2 was not present in the nucleus but was localized in the cytoplasm. Sequencing of Mac-2 cDNAs from normal mucosa and carcinoma revealed no specific mutations that could account for this loss of nuclear localization. We also observed a 5-to 10-fold decrease in Mac-2 mRNA levels in cancer compared to normal mucosa as well as a significant reduction in the amount of Mac-2 protein expressed. These observations suggest that Mac-2 exclusion from the nucleus and its decreased expression may be related to the neoplastic progression of colon cancer.The Mac-2 lectin is a soluble, 32-to 35-kDa phosphoprotein that binds galactose-containing glycoconjugates (1-5). Molecular cloning studies revealed that Mac-2 is identical to carbohydrate binding protein 35 (CBP 35), a lectin characterized initially in 3T3 fibroblasts (3,4,6). It is also identical to IgE binding protein (7) and a 32-kDa tumor-associated lectin (8, 9). The COOH-terminal domain of Mac-2, which contains a conserved carbohydrate binding motif, is homologous to a related family of 14-kDa galactose-specific lectins (reviewed in ref. 5). Collectively, Mac-2 and the 14-kDa lectins are referred to as S-lectins because their carbohydrate binding function was thought to be thiol-dependent (10), an assumption that has recently been questioned (2).The biological functions of Mac-2 remain elusive. Its putative role in cell adhesion has not been substantiated (11). Mac-2 may be associated with cell growth and differentiation because it is found in the nucleus of 3T3 fibroblasts and its nuclear localization may be related to the proliferative state of these cells (5). Also, the expression of Mac-2 occurs as a function of macrophage differentiation (12). These reports are consistent with the recent finding that a homologue of the 14-kDa S-lectin is cytostatic for embryonic fibroblasts (13). Other in vitro studies have suggested that the expression of Mac-2 increases in oncogenically transformed and metastatic cells (14-16).Progress in elucidating the function of Mac-2 has been hampered, in part, by a lack of data on its expression in vivo.In the present study, we found that Mac-2 is largely an epithelial-specific lectin with high expression seen in the colonic epithelium. The progression from normal colonic mucosa to adenoma to carcin...