PCNA and skin basal cell carcinoma: Many studies have reviewed the markers of proliferation, such as p63, Ki-67, c-Met, and PCNA, and their association with morBCC [6,7,14,37,42,51]; however, proliferation is unlikely to be unique to morBCC as opposed to BCC, given that previous studies have noted proliferation indices up to 61% among BCCs in general [88].