Growth inhibition of TEL/PDGFRβ-expressing Ba/F3 cells by CGP53716. (a) TEL/PDGFRβ- or TEL/ABL-expressing cells were seeded at a density of 3.10⁵ cells/mL with or without IL-3 and in the presence of different concentrations of CGP53716 (provided by CIBA-GEIGY, Basel, Switzerland). Cell numbers were determined after 24 hours of culture. (⧫), TEL/PDGFRβ IL-3⁻; (▪), TEL/PDGFRβ IL-3⁺; (▴), TEL/ABL IL-3⁻; (X), TEL/ABL IL-3⁺. (b) In contrast to TEL/PDGFRβ- or TEL/ABL-expressing Ba/F3 cells, control Ba/F3 cells were maintained with IL-3. These cells were either untreated (−) or treated (+) for 18 hours with 0.3 μmol/L of CGP56713. Cell lysates were analyzed by Western blotting using an antiphosphotyrosine antibody.