The v-sis oncoprotein loses transforming activity when targeted to the early Golgi complex

With this system, they demonstrated that productive interactions between v-sis and PDGF receptors occur in a monensin:insensitive site. Since monensin acts by disrupting the structure and function of the trans-Golgi complex, and reduces the rate of transport of proteins to the cell surface (Tartakoff, 1983) , these results indicate that transformation only results when v-sis interacts with receptors in a region past the trans-Golgi complex. However, since monensin is a pleiotropic agent, there may have been other effects on the cells that were not taken into account. Also, the temperature shock required for induction of the hsp70 promoter may have induced other endogenous heat shock proteins.