Smarcd1 is a pivotal subunit of the SWI/SNF complex, and here, we found that differential expression of Smarcd1 exerted little effects on the possible oncogene BRG1, which indicated that Smarcd1 could function as a tumor suppressor independent of other subunits in the SWI/SNF family. This evidence concerns the gene SMARCA1 and neoplasm.