CCN6 and breast cancer: Functionally, deletion of the TSP1 domain (ΔTSP1) abrogated the ability of CCN6 to reduce Notch transcriptional activity, cell invasion, the number of ALDH1+ cells, and the number of tumorspheres formed by MDA-MB-231 and -436 breast cancer cells (Figure 5C-5E, and Supplementary Figure 4B-4F).