AnovelproteinkinaseD-interactingsubstrateof220kDa(Kidins220)orARMSisthefirstidentifiedProteinkinaseD(PKD),aserine/threoninekinase.Kidins220isanintegralmembraneproteinthatisexpressedinbrainandneuroendocrinecells.Kidins220isphsphorylatedbyPKDatserine919invivo.Kidins220hasalsobeenshowntofunctiondownstreamoftheTrksandEphreceptors.