ERBB2 and cancer: The resistant phenotype was characterized at baseline condition by increased expression of ErbB2/HER2, ER, EGFR, and MEK signatures (Table S2A); similarly, at treatment condition, resistant cells showed decreased expression of ErbB2/HER2, ER, and MEK signatures, while signatures of enriched expression of fibroblast predicting cancer progression were included (Table S2B).