SNP309T>G (rs2279744) and SNP285G>C (rs117039649) in the <i>MDM2</i> promoter are thought to have opposite effects on the binding of transcription factor SP1 (specificity protein 1), and consequently on <i>MDM2</i> expression, p53 levels, cancer risk, age at onset, and prognosis.
Two functional SNPs (SNP285G > C; rs117039649 and SNP309T > G; rs2279744) have previously been reported to modulate Sp1 transcription factor binding to the promoter of the proto-oncogene MDM2, and to influence cancer risk.
In contrast, SNP285G>C (rs117039649), located 24 bp upstream of rs2279744, and in complete linkage disequilibrium with the SNP309G allele, reduces Sp1 recruitment and lowers cancer risk.