SPHK1 and prostate cancer: Here we show that similar to hormone refractory prostate cancer cells PC3 and DU14516, in ER-negative breast cancer cells MDA-MB-231 and BT-549 RAD001 alone or in combination with docetaxel, but not docetaxel alone, can downregulate p-P70S6K and SK1 signalling (Figs 2, S1), suggesting the presence of a similar pathway in breast cancer.