They have greatly advanced the research on pterygium and identified several groups of abnormally expressed genes in pterygium, such as keratins (KRT3, KRT4, KRT6B, KRT13, KRT14, KRT16, and KRT24); S100 calcium-binding proteins (S100A8, S100A9, S100A11, and S100P); collagens (COL1A1, COL8A1, and COL10A1). Here, S100A9 is linked to pterygium.