MA currents in HEK293 cells expressing wild-type or mutant PIEZO1. (A) Representative traces of MA inward currents from uninduced (Un) or induced (Ind) stably transfected HEK293 cells expressing wild-type (WT) PIEZO1. Using a patch-clamp electrophysiological technique, functionality of recombinant PIEZO1 channel activity was examined in the whole-cell configuration. Upon a series of mechanical stimulations of a glass probe (1-µm increments, 150-ms step duration), currents were recorded in the whole-cell patch-clamp configuration at holding potential −80 mV. The stimulus waveforms are shown above the current traces. The red lines are MA currents fitted with monoexponential function. (B) Average of inactivation time constant (τ, milliseconds) for wild-type, HX-associated mutant, and known HX-associated mutant (R2456H and M2225R) controls. *P < .05 ***P < .001 (Student t test). (C) Threshold of activation. Several of the mutants studied displayed greater sensitivity to mechanical stimulus as indicated by minimal indentation activation threshold. ***P < .001 (Student t test). n.s., not significant.