IDH1 and fibrosarcoma: As shown in Fig. 5i, the d-2-HG biosensor Bd2HG-1 could detect the increase in d-2-HG levels in the cell culture medium during the growth of HEK293FT cells transfected with IDH1/R132H and of HT1080 cells, a fibrosarcoma cell line carrying an IDH1/R132C mutation33.