tokens: This characterization was done by using a range of functional assays : ( i ) the ability of the protein to bind with p53 consensus sequence using the functional analysis of separated allele in yeast ( FASAY ) ; ( ii ) the ability of the protein to transactivate the p53 - responsive element ( RE ) identified either in the promoter of p21 / WAF1 or in the first intron of BAX , using luciferase reporter assay ; ( iii ) the induction of endogenous p21 / WAF1 gene expression under stress conditions .