MYCN and cancer: Mir-9 is upregulated by MYC/MYCN and plays a role in promoting tumor growth and metastasis in several cancers including breast cancer, osteosarcoma, and rhabdomyosarcoma, where it is often overexpressed (Iorio et al., 2005; Luo et al., 2017) However, in other cancers such as neuroblastoma, miR-9’s role is less clear, and studies have argued for oncogenic and tumor suppressor functions (Laneve et al., 2007; Zhi et al., 2014).