JAG1 and neoplasm: In order to test whether the activation of JAG1 in astrocytes indeed triggers the Notch signalling in tumour cells through cell–cell interaction which is generally required for Notch activation, we first cultured astrocytes in monolayer followed by infecting lentivirus carrying sh-JAG1 or sh-scramble, and the knockdown of JAG1 was confirmed by Western blot after 48 h (Supporting Information Fig S4A).