Taken together, these data demonstrate that there was a predilection for isolating stromal cells over tumor cells from surgical specimens, whereby CM01, CM02, CM03, and CM08-PDCs are deemed non-neoplastic cells derived from the CM tumor microenvironment and will be referred to as CNS Metastasis-associated stromal cells (cMASCs); CM01-PDC-X is an immortalized mouse stromal cell line, and CM04-PDC is an immortalized and transformed tumor cell line derived from a SCLC CM. This evidence concerns the gene PDC and small cell lung carcinoma.