Riboflavin, a component of the B2 vitaminic complex, plays important roles in biochemistry, especially in redox reactions, due to the ability to participate in both one- and two-electron transfers as well as acting as a photosensitizer. Accordingly, low intakes of this vitamin have been associated with different diseases, including cancer and cardiovascular diseases. Riboflavin is thought to contribute to oxidative stress through its capacity to produce superoxide but, interestingly, it can also promote the reduction of hydroperoxides. This peculiar and multifunctional behavior allows riboflavin to take part in various biochemical pathways as a nucleophile and an electrophile, turning it into a versatile and important biological compound.

Protein phosphorylation-dephosphorylation catalyzed by the opposing and dynamic action of protein kinases and phosphatases probably, is the most crucial chemical reaction taking place in living organisms. Protein phosphatases are classified according to their substrate specificity and sensitivity to inhibitory or activator agents, into two families of protein phosphatases: serine/threonine phosphatases and tyrosine phosphatases (PTPs). PTPs can be divided into 3 groups: tyrosine specific phosphatases, dual and low molecular weight phosphatases. The role of tyrosine phosphorylation in mitogenic signaling is well documented, and one would predict that vanadate, pervanadate and other oxidant agents (protein tyrosine phosphatase inhibitors) may act as a growth stimulator.