ERBB2 and breast cancer: In our first attempt to investigate whether we can detect circulating miRNAs in sera of human BC (HER2+, TNBC), cell line-transplanted mice (JIMT-1- and MDA-MB-231-transplanted HTM, see Table 1) under different treatment regimens (with and without irradiation and/or without anti-PD-L1 treatment), we analyzed circulating miRNAs in mice sera, as well as miRNAs from the exosomal fraction of sera, and compared the results to untreated controls and an NSG control (see Table 1).