STIM1 and transient myeloproliferative syndrome: On the other hand, dominant gain-of-function (GoF) mutations in the STIM1 and ORAI1 proteins lead to enhanced SOCE function and constitutive Ca2+ entry in the absence of ER/SR store depletion (Lacruz and Feske, 2015; Morin et al, 2020) that results in tubular aggregate myopathy (TAM) (Bohm et al, 2017; Bohm et al, 2013; Endo et al, 2015; Garibaldi et al, 2017; Harris et al, 2017; Sallinger et al, 2020).