PCNA and neoplasm: Similarly, the expression of genes for cell differentiation (CAV1 for caveolin-1) [59] and cell proliferation (MKI67 for marker of proliferation Ki-67 and PCNA for proliferating cell nuclear antigen) [60,61] were down- and upregulated, respectively, in tumor samples (adjusted p value < 0.01) (Figure 1B).