IRS1 and neoplasm: More broadly, in ΔNp63 overexpressing SSC tumours, unbalanced expression of the TAp63/ΔNp63 isoforms may lead to enhanced Igf-r1/Irs1 transcriptional activation, resulting in augmented protein abundance of IGFR1 and IRS1, which may increase sensitivity of cancer cells to growth factor stimulation (Figure 5).