Comparing the rapamycin-treated FAK shRNA group with the rapamycin-treated REH-empty vector group, the rise in WBC count was significantly slower (p < 0.01; Fig. 5b) and spleens removed from mice sacrificed on day 25 were much smaller in the rapamycin-treated FAK shRNA group (Fig. 5c), indicating that FAK down-regulation increases rapamycin-induced inhibition of leukemia progression in vivo. Here, PTK2 is linked to leukemia.