For example, a study on tumor recurrence found that hypoxia during treating cancer cells with tyrosine kinase inhibitors or cisplatin, which is confirmed by CA9 elevating as a hypoxia marker, induced SCD1 expression in cancer cells, as well as FABP4 in tumor endothelial cells (TECs) and adipocytes in the tumor microenvironment (TME), to inhibit ferroptosis and promote tumor recurrence [58]. Here, CA9 is linked to neoplasm.