A lipid oxidation process proceeding through a series of three successive monooxygenations of the alpha methyl group on the C4 carbon (CH3 to CH2OH to CHO to COOH) and resulting in this overall reaction: 4,4-dimethyl-9beta,19-cyclopropylsterol + 3 NADPH + 3 H+ + 3 O2 = 4-alpha-carboxy, 4-beta-methyl-9beta,19-cyclopropylsterol + 3 NADP+ + 3 H2O.
4,4-dimethyl-9beta,19-cyclopropylsterol-4alpha-methyl oxidase activity