EGFR and colorectal cancer: In the search for a suitable physiological cell system to prove that the EGF/EGFR/Dab1 pathway is functional in vivo we turned our attention to intestinal cells for the following reasons: the lining of the intestine is renewed at a very high rate [41], the stem cell niche which is responsible for this high proliferation rate contains EGF [34], rat intestinal cells express Dab1 [22], and most importantly Dab1 is overexpressed in intestinal cancer and promotes colorectal cancer cell invasion and metastasis [24].