We request funds to support the purchase an instrument that will help more than 19 different laboratories at the University of Washington (UW), Seattle Children's Hospital, and the Fred Hutchinson Cancer Research Center (FHCRC) address critical barriers in their research. The Firefly 3000 Protein Analysis System (Cell Biosciences, Palo Alto, CA) allows all isoforms of a signaling protein of interest to be precisely quantified using sample sizes containing as few as 25 cells. The ability to quantitatively assess cell signaling using very low cell numbers opens the door to assessing signal transduction in rare cell populations obtained after cell sorting or after laser capture microdissection. This instrument will be housed in our Cell Analysis Core Facility at the UW's South Lake Union Campus, using the same infrastructure that supports operation of the Core. In addition, the UW has committed a total of $120,000 over 5 years to support the maintenance of the instrument, assuring that user fees can be kept at relatively low levels. PUBLIC HEALTH RELEVANCE: This application seeks funding for the Firefly 3000 Protein Analysis System. This instrument will support more than 19 labs at the UW, FHCRC and Seattle Children's Hospital, allowing signal transduction to be quantitatively assessed using samples of as few as 25 cells.