PDPN and osteosarcoma: Flow cytometry using LpMab‐21 detected endogenous expression of PDPN by the human cancer cell lines as follows: mesothelioma, NCI‐H226; oral squamous cell carcinoma, HSC‐2 and HSC‐4; squamous cell carcinoma of the lung, PC‐10; and human osteosarcoma, U‐2 OS and MG‐63 (Fig. 4A).