MPL is a cytokine receptor that regulates the production of myeloid cells, in particular megakaryocytes and platelets (Kaushansky, 2005). Dimerization of MPL is important not only for the initiation of signalling (Kaushansky, 2005) but also for the resistance to a recent therapy for myeloproliferative neoplasms (Koppikar et al., 2012). In the current model, cytokine receptors exist as a mixture of monomers and dimers without ligand stimulation, while ligand binding induces additional receptor dimerization (Kaushansky, 2005). However, the dynamics of MPL dimerization remains poorly understood, which is attributed to the limitation of methodologies for analysing the dimerization of a cytokine receptor at a high spatiotemporal resolution. We here employ single-molecule imaging (Liu et al., 2015) of MPL in live cells to solve this methodological limitation.
