Kowalczuk et al. [43] performed a study to understand the role of pro-angiogenic activity of placental growth factor (PFG) in diabetic retinopathy and the effect of a sustained PGF over-expression in rat ocular media, using ciliary muscle electrotransfer of a plasmidencoding rat PGF-1 (pVAX2-rPGF-1). The gene discussed is PGF; the disease is diabetic retinopathy.