NTS and glioblastoma: Consistent with these findings, the pharmacological inhibition or downregulation of CD73 (which mediates the extracellular conversion of NMN to NR) largely abrogates the rescue effects of NMN in FK866-treated OVCAR-3 ovarian cancer cells, A549 lung cancer cells, and U87 glioblastoma cells by impairing the extracellular provision of NR from NMN [32,200].