In another study that used a rhabdomyosarcoma Rh30 mouse xenograft model, a high correlation coefficient was reported between decreases in phosphorylation of threonine residue 70 (Thr70) of 4E-BP1 and tumor growth inhibition with temsirolimus.35 These results suggest that decreases in Thr70 phosphorylation of 4E-BP1 may be a useful surrogate marker for determining inhibition of mTOR activity in tumors. This evidence concerns the gene EIF4EBP1 and rhabdomyosarcoma.