RB1 and neoplasm: The effects of LFN and other DHODH inhibitors on tumor growth, such as brequinar sodium and 4SC-101 have been ascribed to their ability to affect the expression of cell cycle regulators, such as cyclin D2 and pRb expression, the phosphorylation of some proteins, such as protein kinase B, p70S6K, and eukaryotic translation initiation factor 4E-binding protein-1, and/or cellular energy metabolism13,25,27,35.