Hydroxylation of an sp3 C-H bond is one of the ways in which CYP3A4 (and cytochrome P450 oxygenases) affects its ligand.[11] In fact, hydroxylation is sometimes followed by dehydrogenation, leading to more complex metabolites.[10] An example of a molecule that undergoes more than one reaction due to CYP3A4 includes tamoxifen, which is hydroxylated to 4-hydroxy-tamoxifen and then dehydrated to 4-hydroxy-tamoxifen quinone methide.[10] Two mechanisms have been proposed as the primary pathway of hydroxylation in P450 enzymes.