FusionRed is a monomeric red fluorescent protein with an excitation peak of 580nm and an emission peak of 608nm in vitro. It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Entacmaea quadricolor eqFP578 gene, derived by mutagenesis of mKate2. FusionRed shows low toxicity in living cells (PMID:23149748).