The c-kit receptor tyrosine kinase and its ligand, stem cell factor (SCF), play an important role for regulation of mast cells. The symptoms of mouse mutants at either c-kit or SCF gene apparently show the physiological significance of the signal through the c-kit receptor tyrosine kinase. The number of mast cells in the skin of various murine c-kit mutants may be explained by the type and severity of the mutations. All mutations reported in mice and rats are loss-of-function mutations, but we

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... ecently found a gain-of-function mutation of c-kit in mastocytoma cell lines. In these mastocytoma cell lines, the c-kit receptor tyrosine kinase is activated constitutively without binding of SCF. The c-kit receptor tyrosine kinase appears to be important not only for development of mast cells but also for neoplastic transformation of mast cells.