Fig. 4. Paracrine and autocrine effects on keratinocyte proliferation in absence of CTSL. (A) Effects of fibroblast conditioned media on proliferation of ctsl^+/+ (pale gray columns) and ctsl^-/- keratinocytes (dark gray columns). Proliferation was measured by [³H]thymidine incorporation into DNA. ^*P<0.05 compared with all other groups. (B) Effects of keratinocyte conditioned media on proliferation of ctsl^+/+ (pale gray columns) and ctsl^-/- keratinocytes (dark gray columns). ^*P<0.05 compared with ctsl^+/+; ^***P<0.001 compared with all other groups.