Although this simple assay system would be useful to evaluate the effectiveness or efficacy of TDBs simply and could be conducted conveniently in clinical studies, more sophisticated methods to examine IS formation markers, such as PKCθ, CD45, LFA-1, Lck, and ZAP-70, might be necessary to distinguish cell contact-dependent tumor cell killing with IS formation from killing without IS formation [34]. This evidence concerns the gene PTPRC and neoplasm.