Figure 4. Effect of NecB on the expression and activation of AMPK in young and old HDFs. (A) Young and old HDFs were treated with either vehicle (N0), or AICAR (AI), compound C (CC), or 10−20 μg/mL NecB (N10 and N20) for 2 days and the cell lysates were analyzed by western blot for AMPK phosphorylation on Thr172 and total AMPK, using GAPDH as an internal control. (B) The band density was analyzed by densitometry and plotted as the ratio of P-AMPK/total AMPK. (C) AMPK activities in vehicle-, AI-, CC-, or NecB-treated cells were assessed as described in Materials and Methods, and plotted as units/mL. *P < 0.05, **P < 0.01, and ***P < 0.001, compared with vehicle-treated control.