TKT and infection: Data from representative clones demonstrated a single TK-Neo integration site in chromosome 3 between nucleotides 143996100–143996500, which is ~3.5 kbp downstream of the nearest gene (DIPK2A), as well as unique MLV-A3 insertion sites as expected from the independent reactions and low multiplicities of infection that were used initially to establish the clones (S8 Fig).