PCNA and Fanconi anemia: By promoting the monoubiquitination of proliferating cell nuclear antigen (PCNA), RAD18 activates the Fanconi anemia (FA) pathway and recruits TLS polymerases such as DNA polymerase η (pol η) and DNA polymerase ι (pol ι), enabling cancer cells to continue DNA synthesis in damaged genomes (Morocz et al. 2024).