20-HC-Me-Pyrrolidine is a potent Aster protein inhibitor with IC 50 s of 0.11 μM, 0.06 μM, and 0.71 μM for Aster-A, Aster-B, and Aster-C, respectively. 20-HC-Me-Pyrrolidine blocks the ability of Asters to bind and transfer cholesterol. 20-HC-Me-Pyrrolidine also inhibits the movement of low-density lipoprotein (LDL) cholesterol to the endoplasmic reticulum (ER).