MUC4 and breast cancer: This approach was evaluated in a dual JIMT1 (HER2+/MUC4+; resistant to trastuzumab) and SKBr3 (HER2+/MUC4-; control sensitive to trastuzumab) HER2 human BC-bearing xenograft model by molecular imaging techniques 89Zr-Trastuzumab HER2-immunoPET and 18F-FDG PET-CT; as well as measurement of tumor volume and pathological examination (Figure 1).