Recently, several studies have reported the presence of ER whorl-like structures in cultured cells following different treatment conditions. For example, treatment of mouse Leydig cells with the piperazine derivative diethylcarbamazine citrate (DEC), led to the appearance of large lipid droplets, degenerative mitochondria, and giant smooth ER whorls in some cells [25] . Since DEC has been shown to disrupt ER and golgi vesicle transport processes, it could explain the formation of ER whorls. A similar loss of function study leading to the formation of ER whorls was seen in human HeLa cells in which expression of the ER protein Yip1A was knocked down by RNAi [18] . Therefore one of the functions of Yip1A could be to maintain proper ER/golgi membrane networks under normal conditions, but when it is absent, ER membranes collapse into whorl structures.