Effect of GRO/KC treatment on voltage-dependence of K current activation in IB4-negative cells. Data from Figure 2 were converted to conductance values using the calculated value of the K Nernst potential. Data were fitted with the Boltzmann equation. Top: the transient component showed a small but significant leftward shift of V1/2, from 14.3 mV in control cells to 8.8 mV in GRO/KC treated cells (p < 0.0005). The Hill slope values were 10.3 and 11.7 mV, respectively (for e-fold change; difference not significant). Bottom: there was no significant change in the voltage dependence of activation of the sustained component. Best-fit shared parameters were -9.3 mV for V1/2 and 15.1 mV for Hill slope.