Studies are now emerging to suggest a specific function for BMPs in tumour development and progression [38,39] and, although the precise role that BMPs play in this setting remains uncertain, activation of the BMP signalling pathway, typically interpreted as increased levels of phosphorylated Smad1/5/8, has been reported in primary colon carcinoma, non-small-cell lung cancer, renal cell carcinoma and oestrogen-receptor positive and metastatic breast cancers [40,41,42,43,44]. This evidence concerns the gene SMAD1 and neoplasm.