Protocol to prepare E. coli supercompetent cells to transform with plasmid\/ligation. This protocol is originally derived from Hanahan, D. (1983) J. Mol. Biol. 166:557-580 with minor changes. This version works exceptionally well for cloning PCR products where the number of colonies is not expected to be as high as from some ligations. These cells outperform commercially purchased supercompetent cells in my hands.