Melanomas also harbor mutations that promote the malignant phenotype, such as in BRAF, CDKN2A, PTEN, CTNNB1, NRAS, PIK3CA and KIT[5], [6], but except for BRAF (∼50%) and common loss of CDKN2A, these mutations exist in a minor portion of melanoma specimens (10% or less). The gene discussed is PIK3CA; the disease is melanoma.