Y223F mice have unaltered structure of spleen and lymph nodes and functional BTK kinase activity upon stimulation of the BCR. (A) Immunofluorescence staining of spleen and lymph nodes sections. TCRβ (green) and B220 (red) staining in lymph nodes; TCRβ (blue) and B220 (red) staining in spleen. Scale bar 500 μm lymph nodes and 200 μm spleen. (B) Left, western blot on whole-cell lysates from stimulated WT and Y223F B cells. Right, ratio of phosphorylated protein over total protein (as quantified by densitometric analysis) from splenocytes. Splenocytes were stimulated with anti-IgM/H₂O₂ and whole-cell lysates were prepared after 1, 3, 10, and 30 minute after stimulation. None of the comparisons yielded any significant difference.