To examine the effect on lipid droplets, we manipulated the activity of Rabs in the fat body using the Gal4UAS system and a transgene collection of DN and CA forms of all 31 Drosophila Rabs. Lipid droplet size changes were found in many DN- or CA-Rab-expressing larvae, suggesting that these Rabs may regulate the dynamics of lipid droplets. In particular, we analyzed the molecular function of Rab32 and Rab32 GEF/ Claret in lipid storage in detail. We show that Rab32 may affect lipid storage through its effects on autophagy. Lipid droplets are the main storage sites of neutral lipids in all cells, however, the dynamics of lipid droplets are poorly characterized. Here we systematically investigated the functions of all of the 31 Drosophila Rabs in the dynamics of lipid droplets and lipid storage by expressing their DN and CA forms. Eighteen Rabs were identified, 10 of which, including Rab1, had been found in previous proteomic studies. Rab1 is important for ER to Golgi transport by tethering the COPII-coated vesicles through it effector p115. Interestingly, it was reported that COPI and COPII involved pathway delivers ATGL to lipid droplets to mediate lipolysis. Five Rabs are not present in previous proteomic lists. These Rabs may not act on lipid droplets directly and instead may act on other organelles to influence lipid storage. Rab32 is an example of one of these Rabs. Many mutants have been found which have defective eye pigments. Proteins encoded by these genes include enzymes required for eye Sibutramine HCl pigment biogenesis, ABC transporters responsible for the trafficking of pigment precursors, and the so-called ����Yubeinine granule group����. Four granule group genes, encode homologs of different AP-3 subunits which are believed to be involved in protein trafficking into lysosomes. Among them, only rb is required for lipid storage, suggesting that AP-3 subunits may have different roles in the regulation of lipid metabolism. The regulation of lipid storage involves both the biosynthesis and the usage of lipids. Lipids are mainly stored in the lipid droplet, a monolayer-membrane-bound organelle, which is different structurally from lysosomes and lysosome-related organelles. Our studies of Rab32 reveal that the lysosomal pathway and the regulation of lipid storage may converge at points such as lipolysis.