CASP3 and chordoma: In response to HXR9 treatment significantly more cells appeared Caspase-3/7 positive in the recurrent line U-CH1 (77.5%) compared to the primary chordoma cell line U-CH19 (22.5%) and in U-CH11R (69%) compared to the corresponding line U-CH11 (21%), fitting their lower sensitivity to the peptide (Fig. 6c).