Figure 2. PKC_α and PKC_δ, are the only isoforms translocated by PMA in RPE cells. A: Shown is a western blot analysis of the subcellular distribution between cytosolic and membrane fractions of the nine PKC isoforms expressed in RPE cells. RPE protein extracts were fractionated into cytosolic (C) and particulate (P) fractions; 80 µg of protein was loaded in each well. Only PKC_α and PKC_δ were translocated in response to PMA. PKC_δ was completely downregulated by proteolytic degradation by 6 h of treatment, while PKC_α was translocated from the cytosolic to the particulate fraction from 3 h to 24 h. Note that in the doublet obtained for PKC_δ, only the upper band (78 kDa) is the active form of the enzyme. B: Optical density of PKC_α determined by densitometric imaging is shown (Mean±SD; n=4). The contents at different time points are statistically different (F=2.337, p<0.05). The β-actin band with 42 kDa is used for quantitation.