Chun-Ting Liu, J., et al. in February addressed the tendency of heterologously expressed pathway cytochromes P450, including taxadiene 5α-hydroxylase (T5αH) to form multiple products. By structurally characterizing several of these overoxidation products by T5αH, and tuning the promoter strength of T5αH, the number of byproducts were reduced. Also, their study showed that "six previously characterized Taxus genes can coordinatively produce key paclitaxel intermediates", which is available in .