Considering that the active PI3K signaling pathway in tumor cells destabilized FOXO1 protein [17], we treated MCF7 and MDA-MB-231 cells with the phosphatidylinositol-3-kinase (PI3K) inhibitor, LY294002, and found that the expressions of FOXO1 protein and CYP1B1-AS1 were up-regulated (Fig. 2i, j). Here, CYP1B1 is linked to neoplasm.