Doxycycline 1.0 mg/ml (G261) by Applied Biological Materials is a tetracycline-class antibiotic and MMP inhibitor supplied as 5 × 1.0 ml aliquots, used to regulate inducible transgene expression in Tet-On/Tet-Off systems and to inhibit matrix metalloproteinases in cell culture research. Store at –20°C.