Effects of PMA on the activation of PI3-kinase induced by GM-CSF in human neutrophils. The cells were simultaneously treated with BSA (0.01%), GM-CSF (4 nmol/L), and/or PMA (90 nmol/L) for 15 minutes at 37°C. Lysis was conducted under nondenaturing conditions and immunoprecipitation was performed using anti-85 polyclonal antibodies. An in vitro kinase assay was conducted using phosphatidylinositol as substrate. Lipids were separated by TLC, revealed by autoradiography, and quantified by densitometry. Statistical significance was evaluated using unpaired Student's t-test. Mean ± SEM of five independent experiments.