The differential phenotype between Nfat-proficient and Nfat-deficient leukemic cells did not result from a non-specific, toxic effect of tamoxifen treatment or Cre activation since the leukemia initiating potential of ICN1-driven T-ALL that are wild type for all 3 Nfat genes and that carry the RCT2 transgene was unaffected by Tam treatment (S3 Fig; S1 Table). This evidence concerns the gene STIM1 and acute lymphoblastic leukemia.