miniSOG2 is a small (106 amino acid residue) genetically encoded photosensitizer that efficiently generates reactive oxygen species when illuminated by blue light; it has an absorption peak of 430nm in the visible band. It is an engineered derivative of the LOV2 domain of the Arabidopsis thaliana PHOT2 gene (TAIR:AT5G58140), derived by mutagenesis of miniSOG, containing the amino acid substitutions G23S, G40P, Q44R, R57H, L84F, H85R and M89I relative to miniSOG. miniSOG2 does not require any exogenous cofactors (its flavin mononucleotide cofactor is produced endogenously at sufficient levels within cells). miniSOG2 has been used as a light-regulated cell ablation tool; ambient light appears to induce phototoxicity in cells expressing miniSOG2, and thus it may be necessary to maintain animals/cultured cells in the dark prior to blue light illumination (FBrf0234533).