The invasive capability of the spheroids derived from GREM1-silenced SKBR3 breast cancer cells co-cultured with CCD-1068sk breast fibroblasts was significantly reduced compared to that of the spheroids formed by co-culture of CCD-1068sk and control breast cancer (SKBR3-shCtrl) cells (Fig. 3e). Here, GREM1 is linked to breast carcinoma.