GREM1 and neoplasm: Similarly, Gerling et al. [89] showed that activated stromal Hh signalling remarkably reduces tumour burden and tumour progression in mouse CAC models, partly by reducing the levels of secreted BMP inhibitors, such as Gremlin 1 (Grem1) and Noggin (Nog), and by reducing cancer stem cell (CSC) features (Fig. 4).