CD4 and papilloma: However, as had been true of the mice with mAb-induced depletion of these individual T cell subsets, the CD4 KO mice (0/5) (Figure 6A) and the CD8 KO mice (0/5) (Figure 6B) were resistant to papilloma formation when observed for 3 months, as were wild-type (wt) C57BL/6 controls (0/5) (Figure 6C), and did not produce detectable levels of L1 protein in crude skin extracts at this time point (Figure 6D).