Figure 1. Relevant pathways regulate the paradoxical effects of BMP signaling in tumors.

BMP signaling influences cancer cell progression through canonical SMAD and non-SMAD signaling pathways. The canonical SMAD-signaling pathway functions as a stimulator for cancer progression. However, non-SMAD signaling pathways, including PI3K/AKT, MAPK, NF-κB, and JAK/STAT signaling pathways, play bidirectional roles in various cancers. BMP signaling can cause the activation and inactivation of these non-SMAD signaling pathways to promote or suppress tumor progression.