A single mutation at W593 drastically decreased TEL-PDGFβR-transforming activity in Ba/F3 cells. (A) IL-3 independence of distinct TEL-PDGFβR mutants in Ba/F3-derivative stable cell lines. TEL-PDGFβR variants were stably transduced into Ba/F3 cells using retroviral transduction as described in “Materials and methods.” Neomycin-resistant Ba/F3 cells stably expressing distinct TEL-PDGFβR constructs were seeded in RPMI media without IL-3 and counted daily. Ba/F3 cells transduced with empty retroviral vector were included as a control. Data presented are mean ± standard error (n = 4). (B) Expression of distinct TEL-PDGFβR variants in different applied samples of stably transformed Ba/F3 cells. Ba/F3 cells were lysed and TEL-PDGFβR proteins were detected with a rabbit polyclonal antibody recognizing PDGFβR C-terminal tail. Expression of TEL-PDGFβR in each group of 4 independent clones of Ba/F3 stable cells expressing distinct TEL-PDGFβR variants was examined.