DDX53 and neoplasm: Also, Kjaer et al, who investigated the 89Zr-mCD4-F(ab ́)2 fragment in seven preclinical syngeneic tumor models (MC38, CT26, B16F10, 4T1, P815, RenCa, Sa1N), could not show differences in the CD4-derived PET uptake between MC38 and B16F10 tumors.