Enhanced mTORC1 activity in MKs and platelets is associated with age-related increased susceptibility to VTE in mice. (A) Platelets isolated from 4- and 16-month-old mice were stimulated with thrombin (0.2 U/mL) and subjected to western blot analysis for mTORC1 (P-S6, P-P70S6K) and mTORC2 (P-Akt) activities (n = 16). Relative values are provided for immunoreactivity for P-S6, P-P70S6K related to the S6, P70S6K and β-actin signals. Values represent means ± SEM; **P < .01. (B) FACS analysis of MKs from 4- or 16-month-old mice for mTORC1 activity (P-S6, P-P70S6K) (n = 4). Mean fluorescent intensity (MFI) values represent means ± SEM; **P < .01. Images (C), lengths (D), and weights (E) of thrombi that developed in the IVC 48 hours after ligation were measured in 4- or 16-month-old mice treated with rapamycin (1.5 mg/kg per day) for 2 months (n = 6). Values represent means ± standard error (SE). **P < .01.