Table 1. Comparison of the selection efficiency.

Cells	No. positive wells	Expected clone no.	Selection efficiency (%)
Ba/HE+LgIGFP	21	69	30
Ba/Hg+LEIGFP	5	19	26
Ba/neoIGFP	30	67	45

The cells were inoculated into two 96-well plates with an initial cell density of 1 cell/well (for Ba/neoIGFP) or 10³ cells/well (for the others). Number of positive wells out of 192 wells for cell growth is shown. Expected clone number was calculated from the EGFP-positive cell ratio before selection on the assumption that transduction efficiency of an amplifier vector was the same as that of a cognate courier vector in each combination.