(A) CD1 mice were intraperitoneally injected (IP) with PF (75 mg/kg) and sacrificed at various time points thereafter. Hyperphosphorylation of S6K1 T389 (pS6K1) detected at 2 hours suggests that this compound can cross the blood brain barrier. N = 3 per time point. (B) Immunoblots from cortical lysates from CD1 mice treated IP with rapamycin (Rapa, 1.5 mg/kg for 5 days), PF-4708671 (PF, 75 mg/kg for 2 hours), and vehicle (DMSO) alone. Asterisks indicate nonspecific bands, the arrow indicates the pFMRP isoform, laddered bracket indicates the tFMRP isoforms, and S6K1 isoforms are indicated by p85 and p70. (C) Quantification verifies a significant decrease in pS6:S6 but no change in pFMRP:FMRP following mTORC1 or S6K1 inhibition in vivo. *P<0.05 and ** P<0.01 by unpaired, one-sided Mann-Whitney Test. A one-sided test was used considering that decreased pS6 levels were expected. N = 6 per condition. Error bars = SEM.