Previous studies have shown that WT ALK was predominantly expressed in most neuroblastomas and rare in normal cells or non-ALK rearrangement/fusion tumors.42 Consistent with these findings, our research revealed that both mRNA transcription and protein expression level of ALK in non-ALK-rearranged tumors is significantly rare, detectable only in a few tumor cell lines (e.g., H1299, H322, and H1355), and markedly lower when compared to ALK rearrangement/fusion cell lines(see Supplementary Figs. 1, a, 6, a, b). Here, ALK is linked to neuroblastoma.