To further study the relationship between the expression of PeriA and FSP27 in adipocytes, we used an adenoviral system to overexpress human PeriA in cultured 3T3-L1 adipocytes. Overexpression of PeriA resulted in a dramatic reduction in lipid droplet size in cultured 3T3-L1 adipocytes ( Figure 6A ). This reduction in lipid droplet size was accompanied by a decrease in FSP27 protein expression ( Figure 6B ). These observations are consistent with our in vivo data from the WAT of the PeriA Tg mice. FSP27 locates on the surface of lipid droplets much like PeriA and functions to promote the formation of unilocular lipid droplet in white adipocytes  . Interestingly, our western blot data reveal that there is an inverse relationship between expression of PeriA and FSP27 ( Figure 6B ). Furthermore, we analyzed the mRNA expression level for genes involved in adipocyte differentiation, lipid synthesis, and fatty acid β-oxidation in PeriA-overexpressed 3T3-L1 samples. Consistent with our observations in the WAT of Tg mice, we observed down-regulation of Rip140 and up-regulation of Pgc1a . Also, we observed increased expression of genes associated with fatty acid oxidation and mitochondrial biogenesis, and a decrease in the genes associated with lipid synthesis ( Figure 6C ).