Complementation in fused cells reveals 7 genes that cause Xeroderma Pigmentosum nucleus ( DNA Excision Repair after UV Irradiation No DNA Excision Repair after Uv Irradiation cytoplasm XPA WT+ XPA XPA XPA XPA + XPA XPA XPB XPA XPBComplementation in fused cells reveals 7 genes that cause Xeroderma Pigmentosum nucleus = DNA Excision Repair after UV Irradiation cytoplasm = No DNA Excision Repair after UV Irradiation WT XPA WT + XPA XPA XPA XPA XPB XPA + XPB XPA + XPA WT XPA WT + XPA XPA XPA XPA XP XPA + XP XPA + XPA