In addition, it has also been reported that a variety of natural compounds, such as curcumin [23,54,134], quercetin [134], lycopene [134], epigallocatechin-3-gallate [135], vitamin D3 [132,136], dioscin [137], gartanin [123], and flavokawain A [35,122,138,139,140] inhibit the expression of Skp2 and subsequently exert anti-tumor activity. This evidence concerns the gene SKP2 and neoplasm.