An in vivo tumorigenic assay showed that six2 overexpression increased the tumor-initiation capacity of MCF-7 cells, an effect that was fully inhibited by CYP4Z1 or CYP4Z2P knockdown, and the decreased tumor-initiation capacity of MCF-7 cells with six2 knockdown was rescued by CYP4Z1- or CYP4Z2P-3′UTR overexpression (Fig. 7f). This evidence concerns the gene CYP4Z1 and neoplasm.