IMMEDIATE RELEASE

Atto Bioscience Launches Biosensor Technology for GPCR Drug Screening

ACT:One™ Provides a Real-time and Sensitive Measure of cAMP

ROCKVILLE, MD - September 11, 2003 Ð Atto Bioscience, Inc. today announced the launch of ACT:One, a proprietary live-cell technology for G-protein coupled receptor (GPCR) drug discovery. The technology allows extremely sensitive monitoring of intracellular cAMP (cyclic AMP) levels by measuring ion flow across the cell membrane using Atto's newly developed homogeneous-assay membrane potential dye or calcium indicators such as Fura-2 or Fluo-4. ACT:One employs a novel biosensor technology that works with endogenous or exogenous GPCRs coupled to G-proteins of both Gs and Gi families, and provides for high-throughput simultaneous screening of agonists, antagonists and allosteric modulators in either rapid kinetic (3 minutes) or end-point modes (15 minutes, or longer if preferred). The technology can be broadly applied to existing instrumentation including AttoÕs Pathway HT™ high-content bioimager, FLIPR® (Molecular Devices Corporation) or fluorescence plate readers.

Figure: Measurement of cAMP fluxes induced by activation of
endogenous G-protein coupled receptors using the ACT:One technology.

About Atto Bioscience, Inc.

Atto Bioscience, Inc. is a fully integrated life science company applying proprietary single cell imaging and assay technologies to accelerate pharmaceutical drug discovery/development, toxicology, diagnostics, and functional genomics. Atto brings together several core capabilities including real-time confocal 3D live-cell imaging, kinetic single cell monitoring, software design, novel assay development, automation and manufacturing. Founded in 1985, Atto Bioscience, formerly Atto Instruments, is headquartered in Rockville, Maryland. Additional information is available through www.atto.com or (301) 340-7320.

Media Contact:

Philip G. Vanek
Director, Corporate Development
Atto Bioscience