All commercial ATP quantification reagents contain luciferase enzyme and luciferin substrate supplied with a lytic buffer. Cell lysis is necessary to liberate cellular ATP and is typically facilitated by detergents in the buffer. The most useful formulations for HTS applications also contain thermostable recombinant luciferase and ATPase inhibitors which allow for "glow-type" luminescence that produces a sustained signal with a half-life on the order of 5 hr [34, 35] . Prolonged maintenance of the luminescent signal allows for batch processing of plates and obviates any inter-plate kinetic variability.