Complex sentence: PML plays an important role in both p53 dependent and p53 independent apoptotic pathways; it activates p53 by recruiting the protein to a PML-NBs site and promoting its activation, as well as inhibiting regulators of the protein such as MDM2 or HAUSP.
Split into simpler sentences: PML plays an important role in both p53 dependent and p53 independent apoptotic pathways. PML activates p53 by recruiting the protein to a PML-NBs site and promoting its activation, and inhibiting regulators of the protein such as MDM2 or HAUSP.