Thrombopoietin receptor (MPL or TPOR) is, together with the erythropoietin (EPO), growth hormone (GH), prolactin (PRL) and granulocyte-colony stimulating factor (G-CSF) receptors, a member of the type 1 homodimeric cytokine receptor family. MPL protein (635 amino acids) is encoded by the exon 11 of MPL gene, on chromosome 1. It is the human homologue of the v-Mpl, which was firstly discovered, encoded by the murine c-mpl. The murine myeloproliferative leukemia virus (MPLV) infection results in acute myeloproliferative neoplasms (MPN) in mice. MPL is expressed in hematopoietic cells such as hematopoietic stem cells (HSCs), megakaryocytes and their progenitor cells, platelets, as well as in hematopoietic tissues. Approximately 70% of HSCs express MPL and this value decreases during differentiation.
