The anti-tumour antibiotic mithramycin A [29], recent analogues with improved pharmacological and toxicological properties [56], phenethyl isothiocyanate (PEITC) present in cruciferous vegetables [57,58] and acetyl-11-keto-beta-boswellic acid (AKBA) from Boswellia serrata [59] act by disrupting Sp1 binding to GC-boxes, while betulinic acid from white birch bark [60] and green tea phenols [61] reduce the levels of Sp1 or transactivation activity. This evidence concerns the gene SP1 and neoplasm.