Elk1 modulation by diC8-PI(4)P and diC8-PIP₃. (A) Normalized currents compare Elk1 activation at 20 mV before and after the application of the indicated PIP. (B) Fold changes in activation time constant at −20 mV upon the application of 10 µM of the indicated PIP (n = 9, 18, and 10 for PI(4)P, PIP₂, and PIP₃, respectively). (C) Normalized tail currents recorded at −100 mV after a 2-s prepulse to 60 mV before and after the application of 10 µM PI(4)P and PIP₃ (dotted line, zero current). (D) G-V mode shift induced by 10 µM of the indicated PIPs, measured as in Fig. 2 B. All data show mean ± SEM; n = 32, 9, 18, and 9 for control, PI(4)P, PIP₂, and PIP₃, respectively; *, P < 0.05; ***, P < 0.001; t test.