MLH1 and colorectal carcinoma: Studies have documented the role of MLH1 and MSH2 loss in the development of cisplatin and carboplatin resistance in colorectal carcinoma, as well as PMS2 loss conferring low level cisplatin resistance (Aebi et al., 1997; Fink et al., 1997a; Fink et al., 1997b; Martin et al., 2008).