In these combinations, JNK (SP600125) and PI3K (LY294002) inhibitors, abrogated the protective effects of stromal cells on MPN cells in the cell line model (Fig 3) and also in primary BM-derived Lin-CD34+ MPN cells (Fig 4), demonstrating that the integrity of these signalling pathways must be maintained in order for the HS-5 cells to exert their protective effect. Here, MAPK8 is linked to myeloproliferative disorder.