Figure 9. Ethambutol (EMB) induced cytosolic release of cathepsin D in a protein kinase C (PKCδ)-dependent manner in RPE 50. RPE50 cells were untreated (con; B) or treated with 0.8 mM EMB for 0, 0.5, 1, 3, and 6 h (A) or 3 h with or without pretreatment of 2 μM Rottlerin (B). Western blots of total cathepsin D (A) or cytosolic cathepsin D (A, B) were performed using ERK (A) or a nonspecific band in the Ponceau S stained blot (B) as an internal control. The relative ratios of the band intensity of cathepsin D versus ERK (A) or the nonspecific band (B), taking the ratio of time zero (A) or untreated (B) as 1.0, are shown below. The results were an average of three repeated experiments with a C.V. of 6.0–8.0.