Mature human sickle red cells (SS cells) are dehydrated by inappropriate hypoxic activation of erythroid K-Cl cotransporters and of the erythroid Ca2+-activated K+ channel KCa3.1/IK1/KCNN4, also known as the “Gardos channel” [3], [4], [5], [6]. Here, KCNN4 is linked to synovial sarcoma.