In two xenograft models, a doxycycline-inducible shRNA system was used to acutely reduce BRD4 expression after tumors reached 200 mm3 in size; in both cases this led to tumor regression characterized by a strong decrease in phosho-histone 3 (proliferation marker) levels and of the direct BRD4 transcriptional target MYC, and no significant change in cleaved caspase-3. This evidence concerns the gene BRD4 and neoplasm.