Figure 4.

Endocytosis is necessary for the anti-apoptotic function of CXCL12 in hNPCs. hNPCs were pretreated with the endocytosis inhibitor MDC (10 μM) for 1 hour and then pretreated with CXCL12 for 2 hours, hNPCs were then challenged with camptothecin (10 μM) for 4 hours with or without CXCL12. A-F) TUNEL staining was performed to detect the apoptotic cells. Representative pictures from TUNEL assay were shown. G) Quantification data of TUNEL assay was determined as percentage of TUNEL positive cells against total cell number. H) Cleaved PARP protein levels were determined by Western blotting. I) Levels of cleaved PARP were normalized as a ratio of cleaved PARP to actin after densimetrical quantification of panel H and shown as fold change relative to control. Results are expressed as the mean ± SEM of triplicate samples from 3 independent experiments. *, P < 0.05, compared with camptothecin-treated group without CXCL12.