Fig. 4.

The effect of EGF on PIP₃ accumulation in MCF10a cells grown in the presence or absence of arachidonate supplement. (A) Cells were incubated with or without 14.8 μM arachidonate for 24 h (including 6 h starvation) before stimulation with 2 ng/ml EGF or vehicle for 90 s. Data is shown for each PIP₃ species corrected for amount of C36:1 phosphatidylserine in the same sample (mean ± SEM, n = 3). Inset displays total combined species of PIP₃ under each condition. PIP₃/PIP₂ (B), PIP₂/PI (C) and PIP/PI (D) ratios calculated from experiments described in panel A. Levels of PIP₃ and PIP₂ for C38:2 species under archidonate loading conditions were too low to obtain accurate PIP₃/PIP₂ calculations and were thus omitted.