The tumor microenvironment consists of tumor cells, extracellular matrices, immune cells, tumor vessels, and other factors, each with their own crucial role in tumor formation, growth, invasion, and metastasis. Of these, immune cells are considered to be a particularly important factor, as inhibition of immune checkpoints within the tumor microenvironment has been observed to dramatically improve overall survival in patients with cancer. Existing immune checkpoint inhibitors, however, are not always effective for all patients. In order to identify the underlying mechanisms that contribute to immune cell–mediated tumor phenotypes, we are actively working to discover novel molecular targets through the combination of our respective fields of expertise in cell biology, including immunology, neurobiology, and regenerative medicine.