Fig. 5. HGF/SF treatment of apoptotic ARPE-19 cells. (A) ARPE-19 cells were incubated with HGF/SF (50 ng/ml for 48 hours) and subsequently exposed to menadione (50 µM for 2 hours). After 24 hours recovery, cell viability was determined using a XTT assay as described in Fig. 1A. (B) Cells either left untreated or treated with HGF, menadione alone or HGF/SF + menadione as described in (A). AIF immunohistochemistry was performed as in Materials and Methods. The value is the percentage of cells displaying nuclear AIF obtained by an average of three fields per slide in which approximately 150 cells per slide were counted. The results shown are mean +/– std, representative of two independent experiments. (*, P<0.001, ANOVA/t-test, unpaired). (C) Appearance of ARPE-19 cells treated with menadione and HGF/SF as in (A). Immunohistochemistry for AIF and counter-staining with CMXRos or DAPI was performed as in Fig. 4A.