CASP3 and brain cancer: However, the expression of apoptotic cascade proteins p21, Bax, and active caspase-3 was verified as being significantly induced in DBTRG brain cancer cells by PEG-Au-BP treatment, with the quantification results demonstrating p21 at ~4.29-fold (p < 0.01), Bax at ~3.73-fold (p < 0.001), and act-caspase-3 at ~7.19-fold, (p < 0.001).