Since class IIa HDACs are abundantly expressed in leiomyosarcomas (LMS) [15, 34], to confirm the role of HDAC4 in senescence escape, its expression was knocked-out also in low grade LMS cells SK-LMS-1 [35] (Fig. 3a and Additional file 1: Fig. S3a/b). This evidence concerns the gene HDAC4 and leiomyosarcoma.