Psoralen was utilized in the treatment of graft-versus-host disease (GVHD), in a complicated and expensive process known as extracorporeal photochemotherapy. We hypothesized that previously activated psoralen may be a novel treatment for GVHD and is much easier and economical to operate.

Site-directed mutagenesis (Y52E) of POLH has reduced capacity to bypass ultraviolet-induced DNA lesions in HaCaT cells.