Expression of TEL/PDGFβR augments steady-state levels of MAPK signaling pathways in cells grown in IL-3. BaF/3 clone TP2 was cultured in optimal levels of IL-3 for 24 hours in the presence of different concentrations of Tet or with no Tet as indicated and samples prepared directly. Panels A and B represent independent experiments. Immunoblotting was performed to assess the activation status of STAT5, PKB, and the different MAPKs using phosphospecific antibodies as described in Figure 6. The same immunoblots were reprobed as indicated to assess equality of loading.