KRAS is a small GTPase in the RAS protein family that plays a critical role in regulating cell signaling pathways involved in proliferation, differentiation, and survival. KRAS cycles between an inactive GDP-bound state and an active GTP-bound state, and activation occurs through nucleotide exchange from GDP to GTP. Mutations such as KRAS Q61R are frequently associated with human cancers and contribute to abnormal signaling and uncontrolled cell growth. The KRAS Q61R Nucleotide Exchange Assay is a TR-FRET–based assay designed to quantitatively monitor nucleotide exchange activity of KRAS Q61R. The assay detects changes in fluorescence resonance energy transfer generated during nucleotide exchange, enabling measurement of KRAS activation and evaluation of compounds that modulate KRAS signaling for cancer research and drug discovery applications.