Fig. 5. Effect of testosterone. One month after castration (castrated A and B), proliferation markers, phospho-histone H3 (pH3; a,d,g,j), phospho-MEK (pMEK; b,e,h,k) and Cdk4 (c,f,i,l) were very low to undetectable in both p63^+/+ (A) and p63^–/– (B) prostates. Five days after implantation of a 25 mg T-pellet (castrated+T; C,D), all three proliferation markers were upregulated in both p63^+/+ (C) and p63^–/– (D) prostates. In the p63^–/– prostatic grafts, small bud-like outgrowths were visible (D, red arrows). (E) Labeling index for pH3. Data was analyzed with Fisher's PSLD and ANOVA factorial test. Data was indicated as mean+s.d. The bars with asterisk are significantly higher than others (P<0.05). There's no significant difference among bars without asterisk. Both p63^+/+ and p63^–/– prostates were proliferation-quiescent in the intact and castrated hosts. T-treatment of castrated hosts increased pH3-positive cells equally in luminal cells of p63^+/+ and p63^–/– prostates (+T 5 days). However, luminal cells in both p63^+/+ and p63^–/– prostates became proliferation-quiescent one month after T-pellet implantation (+T one month). One month after T-pellet implantation, regenerated p63^–/– prostate expressed markers specific for prostatic luminal epithelium [androgen receptor (AR) (F), and secretory proteins, mouse dorsolateral prostate (mDLP) (G) and mouse ventral prostate (mVP) (H)].