AKT1S1 and diffuse large B-cell lymphoma: In line, the phosphorylation of PRAS40, which is part of the downstream mTOR complex 1 (mTORC1), was reduced in all cell lines, but recovered in the resistant DLBCL cell lines 24 h after treatment (Fig. 4a), suggesting that the resistant cells compensated for the lack of PI3Kβ/δ activity by an alternative way of S6 and PRAS40 activation.