GPX4 and neoplasm: Many derivatives of indirubin have been made in connection with probing their anti-tumour properties, including the development of the first hybrid dual inhibitors [22] of glutathione peroxidase 4 (GPX4) and cyclin-dependent kinase (CDK), as well as molecules inducing damage to DNA and targeting the poly (ADP-ribose) polymerases (PARPs) involved in DNA repair [23].