This proposal is for an EPICS ALTRA flow cytometer/cell sorter from Beckman Coulter (Miami, FL). The instrument is requested to replace an obsolete, and failing, Coulter EPICS 752 that was installed in 1988 and has been in continuous operation ever since. The resource was established to develop and implement analytic techniques for the estimation of tumor and normal tissue cell kinetic and population dynamic parameters using novel flow-cytometric methods. Currently a group of 7 NIH funded faculty members need this resource as major users of the instrumentation. These include long-standing collaborations in tumor and normal tissue studies and more recent studies utilizing molecular techniques, particularly in the area of cell cycle regulatory control. Some of these studies require the introduction of vectors containing genes and gene products. The requested instrument is well suited for making concomitant population dynamic measurements specifically in cells that can be demonstrated to be transfeeted and sorted as needed. The requested instrument is the present state-of-the-art from Beckman Coulter including 12 parameter measurements and full sorting capability. Narrow excitation beam optics and pulse processing electronics will allow for the doublet discrimination and linear accuracy required for the high resolution multi-parameter DNA measurements that are needed for all our dynamic population kinetic measurements. A specialized forward fluorescence detector, specifically developed to aid in the analysis of sperm, is required. This will also aid in the detection of apoptotic cells and will help discriminate between cells and nuclei isolated from solid tissues and tumors. The instrument will be housed within a highly productive specialized flow cytometry laboratory within the Department of Experimental Radiation Oncology, itself a component of the Division of Radiation Oncology at the University of Texas M.D. Anderson Cancer Center (UTMDACC). As well as the 7 major users, 5 other ongoing NIH-funded projects require episodic access to the resource. Unused capacity on this instrument will be made available to UTMDACC faculty and the surrounding community of investigators that need the specialized data acquisition and analytical methodologies.