Genetic deficiency of RSK2 does not affect BCR-ABL induced myeloproliferative neoplasm in a murine BMT assay. (A) Immunoblotting shows protein expression of RSK1 and RSK2 in BM cells from Balb/C WT and RSK2-deficient (RSK2 KO) mice. (B) Kaplan-Meier survival plot of mice receiving either WT or RSK2 KO BM cells retrovirally transduced by BCR-ABL. All BMT mice in the WT group (n = 8) and RSK2 KO group (n = 10) developed an aggressive and rapidly fatal myeloproliferative neoplasm with a comparable latency. The statistical significance for survival was assessed by log-rank. (C) Analyses of mice transplanted with either WT or RSK2 KO BM cells expressing BCR-ABL. (D) Flow cytometric analysis demonstrates an expansion of Gr-1/Mac-1 double-positive mature myeloid cells in spleen (left) and BM (right) consistent with a myeloproliferative neoplasm in representative BMT mice receiving either WT or RSK2 KO BM cells expressing BCR-ABL, with comparable percentages that are supportive of similar disease burdens. (E) Tissue sections of spleen (left), BM (middle), and liver (right) demonstrate evidence of a marked myeloproliferative neoplasm with an expansion of maturing myeloid cells observed in representative BMT mice receiving either WT or RSK2 KO BM cells expressing BCR-ABL. Magnifications are as indicated (H&E).