ERBB2 and cancer: The structurally most similar compounds inhibited mTOR kinase signaling in vitro at 3–4.4 nM [31] and had an IC50 of 31–1700 nM in cancer cell proliferation assays (NCI-PC3, MCF7neo/Her2) [31] compared to our IC50 of 200 nM or 1000 nM in HT-1080 or HeLa, respectively.