INPP4B and Miyoshi myopathy: Since mTORC2 phosphorylates Akt at S473 (21), and RICTOR, a core component of mTORC2, acts as a key effector molecule of the PI3K-Akt pathway (22), we detected the key regulators, including Akt, p-Akt (thr308), p-Akt (ser473), and rictor-mTOR complex (mTORC2) in MM cells with INPP4B gain or loss of functions.