BMPR1B and chronic myelogenous leukemia, BCR-ABL1 positive: In contrast, BMP2 transcript was upregulated in MNC along with BMPR1A (ALK3), BMPR1B (ALK6) and SMADs. These findings support previous findings showing BMP2 is produced by the mature CML polymorphonuclear cells, and CML CD34+ cells are likely to have potentiated signalling in response to ligand16.