H2S upregulates VEGF expression through various angiogenic signaling pathways, such as the mitogen-activated protein kinase pathway, phosphoinositide-3-kinase pathway, NOS/NO pathway, signal transducer and activator of transcription 3 (STAT3) pathway, and adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, playing a role in cerebral vascular development, diabetic wound healing, refractory secondary lymphedema and physiological angiogenesis during pregnancy [195]. Here, STAT3 is linked to lymphedema.