IFNA1 and neoplasm: Since type I and type II interferons (IFNs) are known inducers of PD-L1 expression, which is recognized as a biomarker for α-PD-1 responsiveness on a variety of tumor cells [20, 21], we performed RNA-seq analysis and identified that an IFN pathway signature (both type I and type II) was activated at a significantly higher level in tongue-implanted mEER tumors relative to those on the flank (Additional file 1: Figure S4A and B).