PTEN and cutaneous melanoma: For instance, the tumour suppressor gene PTEN, encoding a dual-specific phosphatase and a member of the PI3-AKT pathway, plays a major role in the pathogenesis of cutaneous melanoma (Guldberg et al, 1997; Stahl et al, 2003), whereas no mutations in this gene have been found in uveal melanoma (Naus et al, 2000).