MAPK1 and diabetic retinopathy: Intraocular PACAP injection attenuates proapoptotic signals (p-p38MAPK and caspase-3, -8 and -12) and promotes anti-apoptotic factors (p-Akt, p-ERK1, p-ERK2, PKC and Bcl-2) in experimental diabetic retinopathy [21].