MSH2 and cancer: Cell viability-based small molecule screening studies reported that 2-benzoyl-6-(2,3-dimethoxybenzylidene)-cyclohexanol (AS13) is selectively toxic to MLH1 deficient cancer cells [38] and that menadione and cytosine-based nucleoside analogs such as cytarabine are selectively lethal to both MLH1 and MSH2 deficient cancer cells [3, 21, 22].