NTRK1 and neoplasm: Indeed, there were a few differences between patient tumor, PDOX, and cell line, such as NTRK1 mutation detected in the autopsy sample of SJ-DIPGX37, but not the associated PDOX or cell line, or MYCN amplification present in SJ-DMGX40 PDOX, but not in the matched patient tumor (Fig. 4 and Supplementary Fig. 2).