TCL1 protein is hyperexpressed in multiple B-cell lymphomas. (A) Expression of TCL1 protein was determined by immunohistochemistry in formalin-fixed, paraffin-embedded primary human lymphoma tissues (FL, n = 5; CLL, n = 2; MCL, n = 3; DLBCL, n = 2; and SMZL, n = 3) and reactive human tonsils (n = 4). Images shown are the original magnification, ×100. (B) Intracellular staining for TCL1 was performed on primary human lymphoma cells and normal human peripheral blood B cells, and samples were analyzed by flow cytometry. The relative expression of TCL1 was calculated as follows: mean fluorescence intensity of TCL1 in test sample/mean fluorescence intensity of TCL1 in normal B cells. Horizontal lines represent the median value for each group. P value on the top of graph represents comparison between normal donor B cells and all lymphomas. P values below the graph represent comparison between normal donor B cells and each lymphoma subtype. All P values were calculated by 2-tailed Student t test (C) TCL1 protein expression was determined by Western blotting in 2 FL and 2 normal donor (ND) peripheral blood B cells. β-Actin protein expression was used as loading control. Vertical line inserted between lanes 2 and 3 to indicate repositioned gel lanes obtained from the same gel.