PCNA and neoplasm: ↑ apoptosis ↑ p21, p16 expression ↓ Bmi-1, c-Myc expression ↑ acH3 ↓ H3K27me3, H3K9me3 at p21 and p16 promoter ↑ H3K4me3, H3K9me3, H3K27me3 HMT activity (SHR cells) ↓ xenograft growth, ↓ tumor weight, ↓ PCNA ↑ p21 mRNA, ↓ c-Myc mRNA