Methyl methanesulfonate and UV sensitive gene clone 81 (Mus81) is a critical DNA repair gene that has been implicated in the development of several cancers including hepatocellular carcinoma (HCC). MUS81 may be a potential therapeutic target for epithelial ovarian cancer (EOC). Mus81 is a well-conserved DNA structure-specific endonuclease that belongs to the XPF/Rad1 family of proteins that are involved in DNA nucleotide excision repair. MUS81 is a key endonuclease involved in homologous recombination (HR) repair after DNA double-strand damage. The nucleolytic activity of MUS81 endonuclease is required for replication fork restart under replication stress elicited by exogenous treatments. Mus81 forms a heterodimer with a non-catalytic subunit, Mms4, in Saccharomyces cerevisiae (Eme1/EME1 in Schizosaccharomyces pombe and mammals).