Figure 3a showed representative IHC staining pictures of 2 cases of lung adenocarcinoma: one with high IHC expression of FSTL1, BMP4, Smad4, and p-Smad1/5/8 and the other with low IHC expression of FSTL1, BMP4, Smad4, and p-Smad1/5/8. Here, BMP4 is linked to lung adenocarcinoma.