These cell line data have driven speculation that mutations must be the primary mechanisms by which cancer targets and inactivates BRG1. Yet, the data from the NIH Atlas database demonstrate that the average weighted frequency (Table 1) and the average unweighted (Table 2A) frequency of abrogating mutations for BRG1 in 23 [13] human tumor types is 0.4 and 0.21%, respectively, out of a total mutation rate of 3.75% (unweighted) and 2.41% (weighted)-which is well below the rate of BRG1 silencing found in many human tumors (15–30%) according to published IHC data (5, 97). This evidence concerns the gene SMARCA4 and neoplasm.