PCNA and skin basal cell carcinoma: Notably, treatment of BCC bearing mice with 4SC‐202 significantly decelerated in vivo tumor growth (Fig. 3h), and markedly repressed the expression of the proliferation marker PCNA, which was paralleled by a moderate reduction of the Hh/Gli target gene and cell cycle regulator Cyclin d1 (Ccnd1)7 (Fig. 3i).