Summary The parent grant (1R35GM126980) for this equipment request supplement is entitled ?Understanding Cell Division.? This award covers the primary research focus of the Gorbsky laboratory, analyzing the mechanics of chromosome movement, the regulation of the mitotic cell cycle, and the characterization of factors and conditions that contribute to chromosome instability. Much of our research involves high resolution imaging of cultured cells expressing fluorescently tagged proteins and are manipulated with RNA interference or CRISPR gene knockout and mutation. The Mizar Tilt light sheet provides high resolution imaging with minimal phototoxicity. The approaches used in the lab to interrogate protein function include siRNA or knocking degron/GFP tags into endogenous genes. We are also using the ?Trim-away? technique, through which a combination of antibody and Trim13 E3 ubiquitin ligase, microinjected into living cells, allows rapid degradation of endogenous proteins without genetic manipulations. The requested upgrade to our Mizar Tilt high resolution light sheet, the recently introduced Tilt-RM resonance mirror, microscope will reduce ?striping? an inherent defect in light sheet microscopy. This modification will greatly enhance the imaging capabilities of the system, particularly for quantitative fluorescence measurements.