IFNG and neoplasm: These 4T1-derived tumour clones expressed equivalent levels of HA and MHC class I, and equally induced HA-specific CTL in vivo, and equally re-stimulated HA-specific CTLs in vitro, despite the impaired IFN-γ responsiveness of 4T1-HAγRDN cells (Fig. 1a–c; Supplementary Fig. 1a–d).