In human, development of melanocytes, erythrocytes, germ cells, mast cells and interstitial cell of Cajal occur through SCF-kit interaction, while ligand-independent auto-phosphorylation of c-kit is typical of a number of tumors, such as leukemias, mastocytosis, gastrointestinal stromal tumor (GIST) and lung carcinomas [16]–[18]. This evidence concerns the gene KITLG and gastrointestinal stromal tumor.