PTEN and cancer: The accumulation of HIF-1α has been associated with cancer causing mutations including loss of VHL or PTEN and activation of signalling via RTK, non-RTK and G-protein-coupled receptor through activation of the PI3K and ERK MAPK pathways in a cell type-specific manner (Zundel et al, 2000; Zhong et al, 2000; Toschi et al, 2008).