Using real time RT-PCR and immunohistochemistry, Peter et al. [36] had already shown that Plk1 can be detected in an activated form in neoplastic MCs, and that either Plk1 silencing or pharmacological inhibition resulted in growth arrest and apoptosis in HMC-1 cells as well as in primary neoplastic MCs from SM patients. This evidence concerns the gene PLK1 and systemic mastocytosis.