Increased phospho-JNK in retinal homogenates from DR rats. Retinal homogenates from control and DR rats at 3 (A) or 5 (B) months after onset of diabetes were subjected to immunoblotting for phospho-JNK, with 50 μg total protein loaded in each lane. Compared to control, DR retinal homogenates showed increased phospho-JNK (54 and 46 kDa) at both 3 and 5 months after onset of diabetes; no increase in total JNK was detected. (C) Densitometric scans indicate that the ratio between SR and GAPDH in DR rats is significantly higher than control (*P < 0.05, **P < 0.05). The results shown are typical of duplicate experiments.