Normalized whole-cell QCa, calculated in response to 50-ms-long step depolarizations, is plotted as a function of depolarization voltage. A Boltzman function was fitted to estimate the V1/2. Individual IHCs are color coded in shades of blue (mean ± SD, N = 34 IHCs from 28 mice, ruptured patch-clamp, 10 mM intracellular EGTA, 5 mM [Ca2+]e). 