Inhibition of PKCα and θ restricts alloreactive donor T-cell expansion and migration to GVHD target organs. BALB/c mice were irradiated at 800 cGy and transplanted with 5 × 106 WT C57CL/6 TCD-BM cells alone (n = 2 per experiment) or in addition to 1 × 106 total T cells from β-actin luciferase transduced C57BL/6 mice and treated twice daily by gavage with vehicle or 40 mg/kg R524 (n = 4 per group per experiment) beginning on day 0 and continuing daily for 2 weeks. Fourteen days posttransplant, recipients were subjected to intraperitoneal luciferin injection and whole body BLI followed by a second luciferin injection, euthanization, organ removal, and BLI of GVHD target organs (A). Bioluminescence was quantified using whole body (B) or whole organ (C) region of interest gating and signal normalization with Living Image software. Average representative whole body images, ex vivo organ images, and average bioluminescence intensities ± SEM depicted are from 1 representative experiment of 2 separate experiments. *P < .05; **P < .01; ***P < .001 (compared with vehicle-treated controls).