Fig. 4.
Effect of time of day of exposure to UVB on skin carcinogenesis (visual diagnosis) in SKH-1 hairless mice. (A) Physical appearance of representatives of the three experimental groups 23 wk after initiation of irradiation. (B) Kaplan–Meier analysis of tumor-free survival. (C) Average number of tumors per mouse following initiation of UV treatments. (D) Average maximal tumor area per mouse in the AM and PM groups.