Western blotting analysis of pp60^c-src expression in PMA-treated CMK cells. CMK cells were treated with PMA. At the time indicated, 5 × 10⁵ cells were harvested and lysed in SDS sample buffer. The presence of c-Src–related proteins in the lysates was analyzed using a purified c-Src polyclonal antibody (c-Src-2; Santa Cruz Biotechnology Inc). The results shown here are representative of three experiments.