BTLA and acute lymphoblastic leukemia: One screened for DEG in clinical samples comparing Z‐fusion (+) ALL and other ALL, and selected cardiotrophin‐like‐cytokine factor 1 (CLCF1) and B‐ and T‐lymphocyte attenuator (BTLA)6; however, the ectopic expression of Z‐fusion proteins did not upregulate both genes very strongly, log2Fold Change <1, in our study and that by others.21