GEMM-ESC protocol published in EMBO Molecular Medicine last year, the Netherlands Cancer Institute (NKI) presented a strategy for rapid analysis of gene function in mouse models by deriving and modifying embryonic stem cells (ESC) from validated genetically engineered mouse models (GEMM), the so-called GEMM-ESC strategy. Now, a detailed protocol is published in Nature Protocols that describes all individual steps. In addition, all materials mentioned in the publication are made publicly available. The complete archive of GEMM-ESC clones is available here at INFRAFRONTIER and can be combined with DNA vectors deposited at Addgene. This unique protocol and resource will likely have a considerable impact on how genetically engineered mice are created in the future.