Integrin-directed migration and the PI-3kinase pathway. integrin-directed migration is dependent on the PI-3kinase pathway. Migration assays were performed with mast cells in the presence or absence of SCF and indicated concentrations of wortmannin and PD98059 inhibitors. Cells were first preincubated with indicated concentrations of inhibitors for 1 hour at 37°C. Thereafter, cells were washed and migration was performed as described in “Materials and methods.” Data are the means ± SEMs of 40 different fields from 2 independent experiments performed in duplicate and are expressed as the average number of migrated cells per field. *P < .05 for untreated versus wortmannin.**P < .05 for untreated versus PD98059.