In agreement with our previous reports [7, 8] but contradicting a report by another group where a trend towards accelerated experimental metastasis in BMP4-treated mice was observed [13], in 231-HM and 4T1.2 tumors that expressed SMAD4, enforced BMP4 expression did not alter tumor growth kinetics (Figs. 2b and S4e). The gene discussed is SMAD4; the disease is neoplasm.