AXL and leukemia: We measured the expression of genes coding RTKs: FLT3, KIT exclusively in leukemia cell lines, PDGFRa, AXL in NB, NTRK1, FGFR3, INSR, ROR2, and RET in both NB and leukemia cells by qRT-PCR, which were top-scoring RTK-coding genes among leukemia and NB cell lines (Figure 2a,b).