Because this reduction in Ifnb1 expression in ATRX-deleted cell lines could, in part, be explained by the 20% reduction in growth rate in vitro after ATRX deletion (Figure 3C), we next tested whether Ifnb1 expression would also be reduced in ATRX-deleted sarcomas in vivo, where no significant difference in growth rates was observed. This evidence concerns the gene IFNB1 and sarcoma.