The preferential tumour vs. plasma localization observed for the ZST316 metabolite and DDAH1 inhibitor L-257 (as indicated by the high AUCtum/AUCpl ratio; Table 7) raises the possibility that the reported in vitro effects of compound ZST316 on vasculogenic mimicry might also depend on its conversion to L-257 in vivo [20,23]. The gene discussed is DDAH1; the disease is neoplasm.