PROS1 and cancer: Besides MDR1, MCL1 was extensively studied in cancer and overexpression, and amplification of MCL1, a Bcl-2 family member anti-apoptotic protein, has been linked with poor prognosis in various solid (Maroufi et al. 2020) and hematological cancers including AML and lymphoma (Wei et al. 2020; Wang et al. 2021).