MAPK8 and myeloproliferative disorder: Inhibition of JNK (Fig 4A and 4C) and PI3K (Fig 4B and 4D) signalling pathways reversed the protective effect of HS-5 cells, although the reversion was not as striking as with the cell line model (Fig 3) and was not seen in all the MPN patient samples (MPN #1; #3 and #6).