PSMB7 and diabetes mellitus: PKC-ζ inhibitorsprevent some of the damage from NMDA activation butPKC-β inhibitors do not inhibit neuronal death.PKC-β is activated in diabetes and appears to be relatedto diabetic retinopathy but the relationship betweenPKC-ζ and diabetes has not been established though it isinteresting to note that PKC-ζ has been associated withupregulation of VEGF in other systems [69, 70].