PTEN and neoplasm: As this tumour suppressor gene is located at chromosome 10q23.3 and melanomas frequently harbour deletions at chromosome 10q22-qter (Isshiki et al, 1993; Herbst et al, 1994; Walker et al, 1995; Healy et al, 1996, 1998) like carcinomas of the prostate (Trybus et al, 1996) and the kidney (Speicher et al, 1994), inactivation of PTEN/MMAC1 has been supposed to occur in melanomas.