Efficient tissue specific recombination of<i>Kras</i> in class switched B cells of <i>AID-Cre-YFP Kras^G12D</i> mice.

<p><b>A)</b> PCR of <i>Kras^G12D</i> allele in B-cells of <i>AID-Cre-YFP Kras^G12</i>^D mice stimulated to undergo class switch recombination <i>ex vivo</i>. Splenic B-cells were stimulated to undergo class switch recombination with lipopolysaccharide (LPS) alone or LPS plus interleukin-4 (IL-4). In contrast to <i>Cγ1-Cre Kras^G12D</i> mice in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0067941#pone-0067941-g002" target="_blank">Figure 2B</a>, recombination was seen following stimulation with LPS+IL-4 or with LPS alone. <b>B)</b> FACS-purification of mature B-cell subsets from <i>AID-Cre-YFP Kras^G12</i>^D mice and detection of recombination by PCR. High-levels of Cre-mediated recombination in B220^lo/CD138+ bone marrow plasma cells (lane 1), B220+/IgM−/GL7+ splenic germinal center B-cells (lane 5) and B220+/IgM−/IgG1+ class switched memory B-cell populations (lane 9) in <i>AID-Cre-YFP Kras^G12</i>^D mice. <b>C)</b> Detection of Cre-activated YFP reporter in cells isolated from spleen and bone marrow of <i>AID-Cre-YFP Kras^G12</i>^D mice given radiation and vitamin D deficient chow. Recombined, YFP-positive cells are plentiful in spleen (6.4%) but rare in the bone marrow (0.20%). Experiment was repeated with three mice and a representative example is shown.