SP4 and cancer: In addition, pharmacologic doses of ascorbate (which induces H2O2), t-butylhydroperoxide and H2O2 also decreased expression of Sp1, Sp3, Sp4 and Sp-regulated gene products in cancer cell lines [26, 50], and a number of other ROS-inducing agents including piperlongumine phenethylisothiocyanate and benzylisothiocyanate also downregulate Sp proteins [42].