WNK2 and hyperuricemia: On the other hand, in hyperuricemia conditions, UA enters vascular smooth muscle cells through an anion transporter [25] and stimulates proliferation by activating mitogen activated protein kinases (MAPK) [26], cyclooxygenase-2 (COX-2) [27], the vascular renin-angiotensin system [28] and the platelet-derived growth factor (PDGF) and PDGF receptors [29].