FMN is futher phosphorylated to FAD Riboflavin is phosphorylated to FMN FMN can be hydrolyzed back to riboflavin FAD can be hydrolyzed back to FMN PathwayStep2343 PathwayStep2342 PathwayStep2341 PathwayStep2340 Vitamin B2 (riboflavin) metabolism GENE ONTOLOGYGO:0006771 Pubmed4915004 Reactome Database ID Release 43196843 Reactome, http://www.reactome.org ReactomeREACT_11070 Riboflavin (vitamin B2, E101) is an essential component for the cofactors FAD (flavin-adenine dinucleotide) and FMN (flavin mononucleotide). Together with NAD+ and NADP+, FAD and FMN are important hydrogen carriers and take part in more than 100 redox reactions involved in energy metabolism. Riboflavin is present in many vegetables and meat and during digestion, various flavoproteins from food are degraded and riboflavin is resorbed. The major degradation and excretion product in humans is riboflavin (Rivlin 1970).