Another study noted that activated ERK signaling induced the transcriptional regulation of hypoxia inducible factor-1α (HIF-1α) to regulate the levels of fibronectin, Col-I and connective tissue growth factors (CTGF) [48], thereby playing a role in multiple pathological processes of DKD such as proliferation, hypertrophy and increased ECM in glomerular mesangial cells. The gene discussed is CCN2; the disease is diabetic kidney disease.