“…Radial growth phase (RGP) melanomas are thin, growing only in or near the epidermis, while vertical growth phase (VGP) melanomas invade more deeply and are competent for metastasis and immortal in cell culture (Clark et al, 1984;Herlyn et al, 1985;Clark, 1991). We proposed a genetic model, in which benign and dysplastic naevi represent p16 and p53-dependent senescence, while melanomas arise by immortalisation of melanocytes (Bennett, 2003;Sviderskaya et al, 2003;Bennett, 2006). Published biological and molecular data (Talve et al, 1997;Keller-Melchior et al, 1998;Glaessl et al, 1999;Rudolph et al, 2000;Hussein and Wood, 2002;Bennett, 2003;Sviderskaya et al, 2003) were consistent with this model, but not conclusive, although a convincing report of cell senescence in melanocytic naevi has appeared recently (Michaloglou et al, 2005).…”