Tamoxifen-dependent recombination. Individual vc2 green-to-red reporter embryos injected with mRNA for PhiC31o (A,D,G) or PhiC31o-ERT2 (B,C,E,F,H,I) are shown. With addition of DMSO alone (B,E,H) no DsRed expression is observed, while addition of 300 nM 4-hydroxytamoxifen (C,F,I) induces recombination and red fluorescence (I), although to a much lesser degree than non-chimeric PhiC31o integrase (G).