SP1 and cancer: Decreased individual expression of Sp1, Sp3 and Sp4 in eight different cancer cell lines resulted in significant inhibition of cancer cell proliferation (Figure 1A), induction of Annexin V (a marker of apoptosis) (Figure 1B), and inhibition of cancer cell migration in a Boyden Chamber assay (Figure 1C) and knockdown of all three genes (siSp1, 3, 4) enhanced the observed responses.