CTLA4 and neoplasm: To determine if responsiveness to IFNβ by TSA cells was required for the therapeutic effect of 8GyX3+anti-CTLA4, IFNAR1 expression was abrogated in TSA cells expressing an inducible shRNA targeting Ifnar1 (TSAshIfnar1) by feeding mice with doxycycline before tumour irradiation (Fig. 2a,b).