MMP9 and diabetic retinopathy: PARP1 is shown to activate JNK and DNA binding of AP-1 in fibroblasts (23) and enhance NF-κB/AP-1 binding to MMP9 promoter sequence in diabetic retinopathy (24), though its role in transcriptional activation of the profibrotic program in Mφ, if any, is not known.