There are pools of Pim-1 and Pim-2 that are associated with SOCS-1 but overcome inhibitory effects of SOCS-1 in v-Abl–transformed pre–B-cells. (A) Shown is an immunoblot of whole cell lysate (WCL) and proteins precipitated with either anti-HA that recognizes HA-tagged SOCS-1 or normal rabbit serum control. The blot was probed with indicated antibodies. (B) Immunoprecipitation using an anti–Pim-1 antibody was performed as in panel A. A blot of WCL, precipitated proteins, and Pim-1–depleted WCL was probed as indicated. (C) Shown is a Western blot of A-MuLV–transformed wild-type and SOCS-1^−/− cells treated with or without imatinib and probed with indicated antibodies. (D) Effects of the expression of SOCS-1 protein on the levels of Pim-1 and Pim-2 were examined by using v-Abl–transformed SOCS-1–deficient or wild-type cell lines. The cells were treated with or without imatinib before addition of IFNγ in a time course. Western blotting shows that SOCS-1 does not inhibit v-Abl–induced expression of Pim-1 and Pim-2 but does have inhibitory effects on IFNγ-dependent expression of these kinases.