EGFR and neoplasm: By recording the expression of EGFP, an indicator of the activation of Tet-HER1-CAR-T cells via RT‒PCR, the tumors collected from the MDA-MB-468-tumor-bearing mice intravenously injected with the Tet-HER1-CAR-T cells Doxy@CaCO3-PEG presented higher EGFP expression levels than those from the mice treated with the Tet-HER1-CAR-T cells and Doxy at Days 2 and 4 (Fig. 3I).