In this assay, flag-tagged N-CoR ectopically expressed in 293T cells was incubated with the extract of H2170 cells, an NSCLC derived cell line that exhibited N-CoR loss, or DMS-79 cells, a SCLC derived cell line that did not exhibit any N-CoR loss, and the level of N-CoR digested during this incubation was determined through western blotting assay. The gene discussed is NCOR1; the disease is non-small cell lung carcinoma.