- The cholesterol-regulated StarD4 gene encodes a StAR-related lipid transfer protein with two closely related homologues, StarD5 and StarD6. Soccio, R.E., Adams, R.M., Romanowski, M.J., Sehayek, E., Burley, S.K., Breslow, J.L. Proc. Natl. Acad. Sci. U.S.A. (2002)