XPF/ERCC4 and ERCC1: their products and biological roles.

At the time of writing, a general search of the literature reveals 259 references that specifically refer to XPF/ERCC4. This puts XPF/ERCC4 around the half way point in a ranking for each of the XP groups based on the number of literature citations in which the specific acronym can be found in the title or abstract. Although such a ranking scheme is somewhat contrived, it is interesting to note that the number of citations for XPF/ERCC4 is very close to that of its mechanistic counterpart, XPG (this relationship is discussed more fully below). The large number of references citing XPF/ERCC4 is reflective of the fact that the cellular roles for Nucleotide Excision Repair (NER) proteins are far more complex than at first imagined and the examination of these diverse functions has begun in earnest taking advantage of a collection of high quality reagents that include antibodies, cell lines and purified proteins and protein complexes. In this chapter we review what has been learned about the cellular roles for XPF/ERCC4. The story is an interesting one, but one far from complete with many questions remaining.