HIF1A and hepatocellular carcinoma: GYY4137, a slow-releasing H2S donor, has been shown to inhibit the proliferation and angiogenesis of cancer cells in HCC cell lines by directly inhibiting the activation of the STAT3 pathway, which in turn inhibits its downstream target proteins, including HIF-1α, and effectively suppresses the expression levels of HIF-1α and its downstream gene VEGF [109].