Because the role of ERK1 and ERK2 in MCs and SM development has not been well investigated, the investigation of the roles played by ERK1 and ERK2 in SM development mediated by TRK and KIT signaling should be explored to determine whether ERK1, ERK2, or both isoforms are required for SM development. The gene discussed is NTRK1; the disease is systemic mastocytosis.