mOrange and mOrange2 are extremely bright orange fluorescent protein monomers which can be used as tags or reporters. Both mOrange fluorescent proteins are mutants derived from mRFP1, a monomeric mutant of DsRed.mOrange excitation and emission maxima are 548 and 562 nm, respectively. mOrange2 excitation and emission maxima are 549 and 565 nm, respectively.