VCP and Cockayne syndrome: Because Cockayne syndrome proteins are suggested to play a role in UVR-induced ubiquitination and degradation of RNAPII [32, 33], we first investigated VCP/p97 function in RNAPII degradation in the presence of CSB by employing corrected CSB-deficient CS1AN cells, which harbor Doxycycline (Dox)-inducible CSB transgenes (Figure 2A).