For the overexpression study, 3T3-L1 cells stably expressing Coxsackie-Adenovirus Receptor (CAR)-3T3-L1 were used as described in Materials and Methods section (A to C). For the knockdown experiments, introduction of siRNA was performed in 3T3-L1 preadipocytes as described in Materials and Methods section (D to F). A, Increase of Oip5 mRNA level by adenovirus-mediated Oip5 gene transfer. B, Incorporation of BrdU in the adenovirus-infected CAR-3T3-L1 preadipocytes at 24 hrs after reseeding. C, Number of adenovirus-infected CAR-3T3-L1 preadipocytes at 24, 48, and 72 hrs after reseeding. D, Decrease of Oip5 mRNA level by siRNA for Oip5 at 24 and 72 hrs after reseeding. E, Uptake of BrdU in siRNA-introduced 3T3-L1 preadipocytes at 24 hrs after reseeding. F, Number of siRNA-introduced 3T3-L1 preadipocytes at 24, 48, and 72 hrs after reseeding. Adeno, adenovirus; Oip5, Opa-interacting protein 5; βgal, β-galactosidase; Cont, control. Values are mean ± SE; n = 6 for each group. *P<0.05; **P<0.01;***P<0.001.