XAB2 protein (XPA binding protein 2) was first identified through its interaction with XPA, a key factor in nucleotide excision repair pathways. XAB2 therefore appears to be involved in transcription coupled DNA repair and transcription. Immunoprecipitation experiments have also demonstrated that a fraction of XAB2 interacts with the transcription coupled repair specific proteins CSA and CSB as well as with RNA polymerase II. Microinjection experiments with XAB2 antibodies resulted in the inhibition of both transcription coupled repair and transcription.