PCNA and pachyonychia congenita: Additionally, in line with the PC cells in vitro, circ_0066147 knockdown led to a distinct decrease in the levels of PCNA and Bcl-2, but an increase in Bax and C-caspase3 in the tumor tissues derived from sh-circ_0066147-transduced PC cells (P < 0.0001; Figure 8d).