XPA to G (xeroderma pigmentosum groups A–G), ERCC1 (excision repair cross complementation group1), RPA1, RPA2 (replication protein A1, replication protein A2) are the main proteins in this pathway and there are two damage recognition arms of the NER pathway: global genome repair (GGR) and transcription-coupled repair (TCR). The gene discussed is RPA2; the disease is xeroderma pigmentosum.