This failure of STIM1/2-deficient CTLs to prevent tumour engraftment was not due to their reduced number since no significant differences of transferred CTLs could be found in the spleens (∼1.5 × 104 WT vs. ∼1.5 × 104 DKO-derived CTLs) and TDLN (∼2 × 103 WT vs. ∼1.8 × 103 DKO-derived CTLs) of mice. The gene discussed is STIM1; the disease is neoplasm.