Dll1/Notch activation contributes to bortezomib resistance by upregulating CYP1A1 in multiple myeloma

► Dll1 activates Notch pathway in myeloma cells mostly through Notch2 receptor. ► Dll1/Notch pathway contributes to resistance to bortezomib in myeloma tumor cells. ► CYP1A1 is upregulated by Dll1 interaction and is involved in bortezomib resistance. ► Notch inhibition and bortezomib treatment prolongs overall survival in 5T33MM mice.