GSTA4 and neoplasm: Although the identification of specific genes that underlie tumor susceptibility loci has been difficult, genes that underlie several modifier loci, including Psl1.2 (Gsta4), Mom1 (Pla2g2a), Pctr1 (Cdkn2a), Skts13 (Aurka), Skts14 (Tgfb1), Mtes1 (Sipa1), and others have recently been identified and variants that affect both function and expression have been reported (reviewed in Angel et al. 2010).