CEACAM1 and colorectal carcinoma: It is, however, known that CEACAM-1 exerts both positive and negative effects on CRC cell growth [34], the latter being in part mediated by the recruitment of cytosolic tyrosine phosphatases PTPN6 and 11 (formerly SHP-1 and SHP-2) through an immunoreceptor tyrosine-based inhibitory motif (ITIM) present in the 72 aa cytosolic tail of the long (L) splice variants [35].