Strikingly, we found that ICAM1 expression marked a subset cells of lung metastases in the PDXs with concurrent gene expression patterns related to metastasis, tumor initiation, and stem cell functions, such as VCAM1, CD34, CD36, ALDH1A1, TSPAN8, and NOTCH4 (Fig. 1b), suggesting ICAM1 may contribute to metastasis initiation of TNBC. Here, NOTCH4 is linked to neoplasm.