GPR68 and myelodysplastic syndrome: RNAi and shRNA screenings have revealed that ribosomal protein S6 kinase (RSK2) and karyopherin beta 1 (KPNB1) are required for lenalidomide and pomalidomide sensitivity in MM cells, respectively [40, 41], while G protein-coupled receptor 68 (GPR68) is essential for lenalidomide sensitivity in del(5q) MDS cells [91].