PCNA and prostate neoplasm: Citrus (Citrus reticulate Blanco) peel extract could induce apoptosis in prostate tumors in a human prostate tumor xenograft mouse model, which was accompanied by mechanistic downregulation of inflammatory enzymes, including inducible nitric oxide synthase (NOS) and cyclooxygenase-2 (COX-2), factors involved in metastasis (MMP-2 and MMP-9), angiogenesis (vascular endothelial growth factor, VEGF), and proliferative molecules (PCNA) [29].