TGFB1 and B-cell chronic lymphocytic leukemia: By contrast, the overall proportion of TGFβ1 expressing cells was significantly increased upon triggering (n = 33, ranging from 0.28 to 99.3 % vs 0.22 to 97.5%, mean 48.45 ± 6.67% vs 42.26 ± 6.39%) (Fig. 2C, connected lines, and Fig. S2C), suggesting that BCR-mediated activation may be involved in the modulatory function of CLL B cells.