CDKN1B and prostate intraepithelial neoplasia: The incidence and multiplicity of PIN progressively increased, respectively, from 11% and 0.16 ± 0.5 in p27+/+ to 60% and 1.5 ± 0.5 (p < 0.05) in p27+/-, and further to 70% and 2.0 ± 0.4 in p27-/- (p < 0.005) mice (Table 3).