derivatives of cholesterol which were oxygenated in the 6 , 7 or 15 positions of the sterol nucleus or in the 20 , 22 , 24 or 25 positions of the sterol side chain were shown to be potent inhibitors of sterol synthesis and reductase activity in the wild-type cells but none of these substitutions had any effect on the 25-hydroxycholesterol-resistant a2 clone .
C0007610
nucleus
C0007634
cells