In contrast, activin A (Inhba), one of the main ligands bound by both FST and FSTL3 was primarily secreted by cancer cells, while its type II receptors (Acvr2a, Acvr2b) were highly expressed in both cancer cells and fibroblasts (Log2 FC > 0.5) (Fig. 4D). Here, FSTL3 is linked to cancer.