tokens: Therefore , we examined the effects of NE - 100 and xestospongin C ( a selective inositol 1 , 4 , 5 - triphosphate ( IP3 ) receptor antagonist ) [ 31 ] in order to investigate the roles of sigma - 1 receptors and IP3 receptors in the mechanisms underlying the enhancement of NGF - induced neurite outgrowth by SA4503 .