ERBB2 and colorectal cancer: Whereas we recently reported that EGFR signaling plays a critical role in proliferation of colorectal cancer cells [26], we next focused on the expression level of EGFR as well as HER2 in several colorectal cancer cells including SW480, DLD-1, HT29 and HCT116, since we observed that the combination use of cisplatin and UV-C synergistically exerts suppressive effect on cell proliferation and apoptosis (Figures 1 and 3).