Figure 2: Identification of a critical regulatory element at the 3′-UTR of the CDKN1A gene (encoding p21) for regulation of p21 expression.

(a) Schematic diagram showing a luciferase reporter with the 3′-UTR of the CDKN1A gene (a 1,539 bp fragment from the stop codon) sub-cloned after the luciferase gene (pMIR-p21-wt or pMIR-1). (b) Serial deletions of the 3′-UTR were created in pMIR-1, resulting in pMIR-2 to pMIR-9. (c) Luciferase activity for different luciferase reporters. Note that a repressor element was present at the region from +1,500 to +1,515 of the 3′-UTR of the CDKN1A gene.