Whereas we recently reported the availability of UV-C alone (30 J/m2 and more) in human colorectal cancer cells, in which we showed that UV-C can evade these cells from oncogenic stimulation of EGF by decreasing the EGFR protein level [26], we herein investigated the combination use of low dose cisplatin and low dose UV-C on cell growth in human colorectal cancer cells (SW480, HT29, DLD-1 and HCT116) and found that the combination has synergistic effect on cell growth inhibition by down-regulating receptor tyrosine kinases, such as EGFR and HER2. The gene discussed is ERBB2; the disease is colorectal cancer.