CEACAM5 and cancer: The ability of the different CEA-4-1BBL fusion proteins to bind these CEACAM5+ human cancer cell lines was assessed by flow cytometry using a binding assay, as described in Figure 1C. The measured binding as median fluorescence intensity (MdFI) showed that Sm9b-4-1BBL and its parental variant, MFE23-4-1BBL, displayed similar MdFI values, which were higher than for A5B7-4-1BBL or T84.66-LCHA-4-1BBL (Figure 1E, Supplementary Table S2).