MTOR and breast cancer: Given that eRF3 controls not only translation termination and NMD but is also involved in other cellular pathways including cell cycle, mTOR signalling, apoptosis and mRNA deadenylation (12,54–57) and that SUP35, the gene encoding eRF3 is essential for yeast viability, it seems surprising that CC-90009 should show low toxicity to cultured human fibroblasts, keratinocytes, myoblasts and HDQ-P1 breast cancer cells.