PIK3CB and nasopharyngeal carcinoma: Interestingly, in microdissected NPC, PTEN mutation is the most common event of the PI3K aberrations (5/28 PI3K mutated tumors), followed by mutations of a diverse group of PI3K players, such as PIK3CA (4/28), PIK3C2G (4/28), MTOR (2/28), PIK3R4 (2/28), PIK3AP1 (2/28)., PIK3CB/G (2/28 each), TSC1 (2/28) and RICTOR (2/28).