BASH reconstitution of BASH-deficient pre-B-cell lines promotes κ chain expression, down-regulates pre-BCR expression, and reduces cell size. BKO84 cells were infected with retroviruses containing pMX-IRES-GFP (GFP) or pMX-BASH-IRES-GFP (BASH/GFP) and analyzed by flow cytometry 4 days after the infection. (A) Expression of GFP in total live cells (left panels) and of κ chain on the GFP-positive cells (5000 gated cells; right panels). Numbers above the horizontal bars in the histograms indicate the percentages of the gated population. (B) FSC of and pre-BCR expression on the gated GFP-positive (bold line) and GFP-negative (dotted line) cells. (C) The frequency of κ-positive cells among GFP-positive (▪) or GFP-negative cells (□) in BKO84 cells 4 days after infection with GFP or BASH/GFP retroviruses. Bar graph indicates mean value (± SD) of 18 independent experiments. ^*Determined by Student unpaired t test.