NPTX2 and thymoma: (2) Since there are no thymoma or NETCC cell lines and only a few TC cell lines, we were unable to perform in vitro experiments, including re-expression by a methylation inhibitor treatment (5-aza-2′-deoxycytidine), or assays on colony formation, apoptosis, and proliferation using the exogenous up- and downregulation of NPTX2.