PCNA ubiquitination-independent activation of polymerase η during somatic hypermutation and DNA damage tolerance

► Polη can be activated dependent and independent of PCNA-Ub during both SHM and DDT. ► PCNA-Ub and Polη are necessary, but not essential, for efficient DDT of UV-lesions. ► PCNA-Ub/ Polh independent DDT of UV-lesions involves Rev1 and Rev3.