Figure 6. Schematic representation of the interactions between DDB2, p21 and PCNA. (A) DDB2 interacts directly with PCNA through a conserved PIP-box, while the binding to p21 is mediated by PCNA. For simplification, other NER factors have not been drawn here. (B) DBB2 is first recruited to DNA damage sites and, after the recognition step, interacts with PCNA which then promotes its proteolytic degradation.