SLiCE cloning stands for Seamless Ligation Cloning Extract and is based on an in vitro recombination process directly in E. coli cell extract. To enhance the cloning efficiency, this extract is usually prepared from an E. coli strain that expresses components of the λ prophage Red/ET recombination system. In a first step you’ll perform a PCR with primers that contain 5’ extensions to create a PCR fragment with short homologies to the area of the vector where you’d like to insert your gene of interest. The vector can be linearized via PCR as well (or alternatively, with a restriction enzyme). Both vector and insert fragment are mixed with the cell extract to perform the SLiCE reaction, after which the mixture is transformed into an E. coli cloning strain.