Another study performed single-cell sequencing analysis on 6 chordoma cases and revealed that the TGF-β signaling pathway was not only essential on the progression of chordoma, but also induced the malignant progression of tumor cells to extracellular matrix (ECM), maintained the tumor stem cells self-renewal, promoted the change of extracellular matrix (EMT) and the transformation of CD4+T cells to Treg+ cells in chordoma (19). This evidence concerns the gene CD4 and chordoma.