It has been suggested that, similar to the UvrD helicase involved in TC-NER in E.coli, the DNA helicase activity of TFIIH complex may facilitate damage-stalled RNA polymerase II (RNA Pol II) backtracking (Epshtein et al. 2014). RNA Pol II backtracking, together with the cleavage of the 3' protruding end of nascent mRNA, might promote the movement of the transcription bubble away from the transcription-coupled nucleotide excision repair (TC-NER) site, while an open bubble is created (Sarker et al. 2005, Hanawalt and Spivak 2008). Once the open bubble is generated, the RPA heterotrimer composed of RPA1, RPA2 and RPA3 coats the undamaged single strand DNA (ssDNA) (de Laat et al. 1998), thereby protecting it from endonucleases. The interaction of RPA with XPA facilitates RPA recruitment to the nucleotide excision repair (NER) site (He et al. 1995, Ikegami et al. 1998). A DNA endonuclease ERCC5 (XPG) is recruited to the TC-NER site through its interaction with the stalled RNA Pol II (Sarker et al. 2005), the TFIIH complex (Dunand-Sauthier et al. 2005, Zotter et al. 2006, Ito et al. 2007) and the RPA heterotrimer (de Laat et al. 1998).