ERBB2 and breast cancer: To examine the specific effects of ganetespib on ErbB2 protein stability in the ErbB2+ breast cancer cells, we treated BT474 and SKBR3 cells with cycloheximide (CHX; 100 μg/mL), an inhibitor of protein synthesis, alone or CHX + ganetespib (1 μM) for the indicated timepoints.