The objectives of this work were to identify potential roles of the XPG protein in ribosomal DNA transcription, but also in rRNA maturation, by studying these processes in both wild type and XP-G/CS cell lines, hoping to open new therapeutic pathways for the combined disease of Xeroderma Pigmentosum and Cockayne Syndrome. The gene discussed is ERCC5; the disease is xeroderma pigmentosum.