PKD1L1-AS1 and chordoma: These included the embryonic notochord markers ACAN, COL2A1, SOX9, and TBXT themselves, which are abnormally active in chordoma cells (30); TPX2, C7orf69, WEE1, ATP6V1B2, and SAE1, which are controlled by binding of TBXT to their superenhancers (7, 8); collagen genes associated with the embryonic notochord (COL17A1 and COL26A1) (31) or chordoma (COL11A2) (32); and the chordoma-associated cytokeratin genes KRT18 and KRT19 (8, 30) (fig.