CD44 is overexpressed on leukemic cells of Tcl1-tg mice compared with healthy B cells of wild-type mice and is associated with organ infiltration. (A) CD44 surface expression on viable CD5⁺/CD19⁺ leukemic cells of Tcl1-tg mice and CD5⁻/CD19⁺ healthy B cells of C57BL/6J wild-type mice was assessed by flow cytometry (mean fluorescence intensity ratio, MFIR). (B) CD44 expression on CD5⁺/CD19⁺ cells in lymphoid organs of Tcl1-tg mice correlates with the percentage of CD5⁺/CD19⁺ CLL cell infiltration in spleen (SPL), liver (LIV), and blood (BL) but not BM, lymph node (LNP), and PC. Pearson correlation was determined.