Activity of FAK (a, c) and STAT3 (b, d) in c-Kit+bone marrow cells from leukemic mice. The phosphorylation status of FAK and STAT3 was determined by Western blot analysis. (a and b) show bone marrow cells from wild-type recipients, (c and d) show bone marrow cells from Shb knockout recipients. Activation was evaluated by immunoblotting for phospho- and total FAK and STAT3 respectively. Protein phosphorylation was related to total protein content on the same blot and signal strength was estimated by densitometric analysis. Means are presented in arbitrary units ± SEM and are based on 6 mice of each genotype in 2 independent experiments. * denotes p < 0.05 respectively as determined by Student’s t-test.