| In cultured granule cells 7 days in vitro , Cupidin was present as synaptic and extra synaptic punctate clusters that largely co localized with the actin cytoskeletal binding partners F actin and drebrin , as well as a post synaptic scaffold protein PSD 95 . ^^^ The glutamate induced declustering of Cupidin preceded that of F actin and drebrin , was elicited by NMDA receptor mediated Ca2+ influx , and was followed by a downstream pathway including MAPK / ERK and protein tyrosine kinase . ^^^ |