Plug and socket technology

and then

 

redrawn by SPW from Detloff, P. J., J. Lewis, S. W. John, W. R. Shehee, R. Langenbach, N. Maeda and O. Smithies 1994. Deletion and replacement of the mouse adult beta-globin genes by a "plug and socket" repeated targeting strategy. Mol Cell Biol. 14:6936-6943
Lewis, J., B. Yang, P. Detloff and O. Smithies 1996. Gene modification via "plug and socket" gene targeting. J Clin Invest. 97:3-5