NRTN and neoplasm: OS has many subtypes, and different subtypes of OS display various histopathological patterns and clinical behaviour and would have different tumour microenvironment and gene expression profile.1 Using 16 Cancer Cell Line Encyclopedia (CCLE) datasets of OS cell lines, we showed varying expression levels for the four pain-associated genes (ARTN, GDNF, NRTN, and PSPN; Figure 6).