Staining of the cytospin preparations of the four patient-derived melanoma cell lines showed two cell lines (Ma-Mel-46 and Ma-Mel-54a) expressing almost all of the three receptor tyrosine kinases tested in a weak to strong pattern (besides Ma-Mel-46 staining negative for PDGF-Rα), whereas the other two cell lines (Ma-Mel 52 and Ma-Mel-59a) were nearly negative for those molecules (besides Ma-Mel-59a staining positive for PDGF-Rα) (Table 4; Figure 3). Here, NTRK1 is linked to melanoma.