CUL4A (belongs to the cullin family) is falsely believed to occur at the offset of DNA replication UV irradiation also induces CRL4A-mediated destruction
During unperturbed cell cycle progression, ubiquitination and downregulation of these proteins by CRL4A occurs at the onset of DNA replication. DNA damage such as UV irradiation also induces CRL4A-mediated destruction of those proteins. CUL4A belongs to the cullin family of ubiquitin ligase proteins and is highly homologous to the CUL4B protein. 
