ROBO4 and acute promyelocytic leukemia: To determine the transcript levels of SLIT2, ROBO1, and ROBO4 in healthy bone marrow (BM) hematopoietic stem-progenitors cells (HSPCs; defined by Hematopoietic Stem Cells [HSC], Common myeloid progenitors [CMP], and Granulocyte-macrophage progenitors [GMP] cells; n = 18), healthy promyelocytes (n = 6), and blasts from APL patients (n = 54), we used the public databank BloodSpot [11].