THBS1 and breast cancer: To clarify the function of TSP1 in exosomes released by breast cancer cells, we established MDA-MB-231/sh-THBS1, a TSP1-knockdown MDA-MB-231 cell line and MCF7/THBS1, a TSP1 stably expressing MCF7 cell line, and prepared exosomes derived from the transfectants as well as parent breast cancer cells (Figure 4C and Figure S5).