Loss of PTEN seems associated with unresponsiveness to targeted therapy against EGFR in colorectal cancer and glioblastomas (Mellinghoff et al, 2005; Frattini et al, 2007; Negri et al, 2010), moreover it predicts resistance to trastuzumab in HER2-positive breast cancer (Nagata et al, 2004; Pandolfi, 2004). The gene discussed is PTEN; the disease is colorectal cancer.