Probably a lot more of their biology in normal cells and cancer cells has to be understood in order to design better inhibitor molecules and clinical trials [48–51]. Drugs being tested for tumors other than the FDA approved scenarios in the case of receptor tyrosine kinases are listed in table 1 and examples of inhibitors of each receptor can be seen in figure 1 (Table 1, Fig. 1). This evidence concerns the gene NTRK1 and cancer.