KITLG and anemia (phenotype): The receptor tyrosine kinase c-kit and its ligand Stem Cell Factor (SCF, also c-kit ligand, Steel factor or mast cell growth factor) are essential for hematopoietic development since mice lacking functional c-kit (White Spotting or W mutants) or SCF (Steel or Sl mutants) die of a severe anemia in utero[14], [20].