BMP4 and neoplasm: For example, BMP-2 and -4 inhibit prostate cancer cell growththrough Smad-1 phosphorylation, p21WAF1/ cip1 up-regulation, and Rbdephosphorylation, while in glioblastoma, BMP4 and its cognate receptors cantrigger the Smad signaling cascade to reduce the proliferation of tumor cells[16].