FMR1 and fragile X syndrome: One group that focused on voltage-gated calcium (Cav) channels in FXS-iPSC-derived NPCs and Fmr1 KO mouse NPCs found that the intracellular calcium release signaling in response to membrane depolarization was increased in both human and mouse NPCs lacking FMR1 expression at an early stage of differentiation (day 1) [63].