ATP2A3 and lung carcinoma: Decreased intra-ER calcium levels, as observed in differentiated gastric and lung carcinoma cells, are compatible with increased SERCA3 expression, for example, in a scenario in which SERCA3 overexpression is part of a process whereby a new, SERCA3-associated ER sub-compartment is created during cell differentiation, including the formation of new ER membrane surface area and ER lumen volume.