Recently, expression analysis of surface marker proteins and the master transcriptional regulators T-box transcription factor 21 (TBET) and GATA binding protein 3 (GATA3) in patient samples and the TCL1 AT mouse model revealed a more severe accumulation of Th1-like T-cells compared with Th2 cells in CLL [17]. Here, TBX21 is linked to B-cell chronic lymphocytic leukemia.