IGFBP3 and triple-negative breast carcinoma: Conversely, under conditions of cell survival (e.g. an absence of apoptotic stimuli), activation of the EGF receptor, a pro-survival tyrosine kinase, is potentiated by endogenous IGFBP-3 in several triple-negative breast cancer cell lines as well as MCF-10A, an effect requiring sphingosine kinase 1 and mediated by sphingosine-1-phosphate [16, 44].