MDK and malignant mesothelioma: As shown in Figure 1A, MDK was detected in HEK293 cells, H441 lung adenocarcinoma cells and H520 human lung squamous cell carcinoma cells but not in A549, H322 and H358 lung adenocarcinoma cells, SQ5 lung squamous cell carcinoma cells or MESO-1 malignant mesothelioma cells.