PTPRO and plasma cell myeloma: Notably, this finding was not restricted to bortezomib, as ANBL-6 cells over-expressing wt PTPROt also had increased levels of Caspase cleavage after exposure to cisplatin (Figure 3D, left and right panels), and melphalan (Figure 3D, right panel), both of which are commonly used chemotherapeutics against myeloma.