Ecdysone receptor (EcR) and its heterodimer, ultraspiracle protein (USP), are ligand dependent transcriptional factors. Transcriptional factors are frequently subjected to phosphorylation. Both USP and EcR have been shown to be phosphoprotein and their phosphorylation is mediated by protein kinase C (PKC). PKC-mediated phosphorylation has recently been demonstrated to play an important role in 20 hydroxyecdysone (20E)-induced gene expression in Drosophila melanogaster. In present study, the effect of PKC-mediated phosphorylation on subcellular translocation of USP and EcR in salivary gland of Drosophila melanogaster was investigated and its role in regulating the function of the EcR/USP complex is discussed.