To further verify the effect of PAI-1 on the EMT process in breast cancer cells, PAI-1 was depleted with siRNA or stably silenced in MDA-MB-231 cells and the knockdown efficiency was determined by qRT-PCR (Figure S1), followed by western blot or immunofluorescence analysis to determine the alteration in EMT-related markers. The gene discussed is SERPINE1; the disease is breast cancer.