MXRA5 and aortic stenosis: Furthermore, MXRA5 is a new ECM biomarker for calcified aortic valves, and its increased expression level leads to aortic stenosis, which in turn induces the development of HF.[22] Lumican (LUM) is a proteoglycan secreted by the ECM that regulates collagen fibril formation and is highly expressed in HF patients and mice.