MDK and neoplasm: For the MDK-HER2 fusion, although a formalin-fixed and paraffin-embedded (FFPE) sample of 431-9540474 T was unavailable for the multicolor FISH analysis, the whole genome sequencing data suggested a mixture of tumor cell populations harboring gene amplifications of wild-type HER2, MDK-HER2, and wild-type MDK (Figure 3).