Abstract
We present here a protocol for biallelic tagging of an endogenous gene in human cells using CRISPR-Cas9 editing technology. Using RIF1 as an example, we describe tagging the gene with a mini-auxin-inducible degron and a green fluorescent protein at its C terminus. We detail steps for preparing and designing the sgRNA and homologous repair template, and clone selection and verification. For complete details on the use and execution of this protocol, please refer to Kong et al.1.