PBX1 and hydrops fetalis: Since NAD is a major shared substrate between SIRT1 and PARP1, we generated PARP1-, PBX1-, and PARP1 + PBX1-overexpressing HF-MSCs to ascertain whether the PARP1–SIRT1 axis plays a role in PBX1-mediated alleviation of cellular senescence and apoptosis.