Current-voltage relationships in undifferentiated ReNcell VM. A) Example of voltage responses from a resting potential of ~-80 mV to current steps of increasing amplitude in a cell (50 pA steps from 50 pA to 500 pA, 400 ms duration). B) Current responses to voltage steps of 10 mV, from the holding potential of -60 mV to +30 mV, in the same cell shown in A). C) Average voltage-current relationship for the peak (solid squares) and the steady (open squares) current in undifferentiated ReNcell VM (n = 4). The lines represent linear regressions of the two data sets with r2 > 0.99 in both cases.