Functional properties of MUNC13-4 mutants identified in case #1 (P6) and #2 (P11) and reconstituted in Unc13d KO mouse CTLs. (E) Degranulation assay, as measured by LAMP-1/CD107a externalization of Unc13d deficient mouse CTLs transduced with E379K-MUNC13-4, using SIINFEKL peptide-pulsed EL4 target cells.