Fig. 6From: Cancer-associated fibroblast-derived Gremlin 1 promotes breast cancer progressionGREM1 knockdown in 19TT breast cancer-associated fibroblasts (CAFs) impairs breast cancer cell invasion in a 3D spheroid invasion model. a, b Collagen invasion assay of co-culture spheroids. Eight spheroids per indicated group were embedded into collagen. Left, representative images of 3D spheroid invasion at days 0, 2, and 4. Red, MCF7 (a) or MDA-MB-231 (b) cells; blue, 19TT cells with/without GREM1 knockdown. Right, relative invasion area was quantified as the area difference at days 2 and 4 relative to that at day 0. The results are expressed as the mean  ± s.d., n = 8. Student’s t test, *P < 0.05, **P ≤ 0.01Back to article page