OGN and meningioma: OGN is regarded as a novel oncogene in meningioma development.8 The OGN protein induces meningioma proliferation by down-regulating NF2 and activating mTOR signaling.8 Therefore, we used a western blot assay to evaluate the expressions of OGN, p-mTOR, and NF2 in cells after 48-h exposure to different concentrations of chrysophanol (p< 0.05, Figure 3).