Kilgore S. showed a high expression of cyclin D1, a key regulator of cell cycle-progression in a series of 26 chordoma samples (9); overexpression of CDK4, p53 and MDM2 was detected in 20–56% of sacral and skull-base chordoma, with a poor prognostic significance (10). The gene discussed is TP53; the disease is chordoma.