ERBB2 and breast cancer: To determine the interplay between DEPTOR and ErbB2 in breast cancer cells, we first measured the protein levels of DEPTOR and ErbB2 in multiple breast cancer cells and found that both ErbB2-positive BT474 and MDA-MB-361 cells showed a high expression of DEPTOR and ErbB2, while ErbB2-negative MCF7 cells showed a moderate expression of DEPTOR (Figure S1A).