Likewise, the clinical trials discussed above provide evidence to suggest that ovarian cancers with coexisting PIK3CA and MAPK pathway mutations may be sensitive to PI3K pathway inhibition, whereas colorectal cancers harboring the same repertoire of mutations affecting these genes may be resistant (Di Nicolantonio et al., 2010; Janku et al., 2011, 2012). The gene discussed is PIK3CD; the disease is ovarian cancer.