Figure 1. NecB treatment increased the cell viability of young and old HDFs. (A) Young (PD of 20) and near-senescent (PD of 72, old) HDFs were treated with vehicle (PEG) or various concentrations of NecB for 2 days and the cell viability was assessed by MTT assay. (B) Young and old HDFs were treated with 10 and 20 μg/mL NecB for 2−4 days and the cell viability was assessed by MTT assay. *P<0.05, **P<0.01, compared with vehicle-treated control.