Binding of TP53 (p53) to p53 response elements in the first and second introns of the IGFBP3 gene upregulates IGFBP3 transcription (Buckbinder et al. 1995). IGFBP3 is one of a family of six homologous proteins that bind IGF1 and IGF2 with high affinity. IGFBP3 contributes to cellular apoptosis in both IGF-dependent and IGF-independent manner (Marzec et al. 2015).