Comparison of siRNA-mediated knockdown of ATGL, adiponutrin (AN), and HSL in fully differentiated 3T3-L1 adipocytes. 3T3-L1 adipocytes were electroporated in the presence of control siRNA or siRNAs specific for ATGL, adiponutrin, or HSL, alone or in combination at day 7 of differentiation (n = 3, representative one of two experiments). ATGL (A), adiponutrin (B), and HSL (C) expression were determined by Q-PCR 48 h later. Gene expression was normalized to 18S ribosomal RNA and expressed relative to ATGL expression in the control group. Basal (D) and stimulated (E) glycerol release and basal (F) and stimulated (G) NEFA release were determined at day 9 of differentiation. Glycerol and NEFA release was normalized to total cell protein and expressed relative to the nonstimulated control group. Iso, isoproterenol. *P < 0.05; **P < 0.01; ***P < 0.001; **** P < 0.0001.