RPS6KB1 and familial dilated cardiomyopathy: An increase in the phosphorylation of mTOR1Ser2448 was observed in the DCM hearts (Fig. 3b, c), in conjunction with an elevated phosphorylation of p70S6K (Fig. 3b, d) and P-IRS1ser636/639 (Fig. 3b, e), the down-stream targets of mTOR.