Figure 2. R406 induces apoptotic cell death in senescent HDFs. (A) Cell morphological change. Senescent (S) HDFs were plated in 6-well plates at a density of 6×104 cell per well and non-senescent (NS) HDFs were plated in 6-well plates at a density of 8×104 cell per well. And then, the HDFs were treated with DMSO or R406 (2, 10 μM) for one day. Images were randomly captured by inverted microscopy (scale bar: 100 μm). (B–D) Senescent and non-senescent HDFs were treated with DMSO or R406 (10 μM) for one day and then western blot assays were conducted to determine changing expression levels of apoptosis regulating factors. (E, F) Senescent and non-senescent HDFs were respectively treated with DMSO, R406 (10 μM), and staurosporine (100 nM) for one day and apoptosis assays with Annexin V/PI staining were conducted.