Fig. 2. BCR activation, but not store depletion, induces Ba²⁺ entry in DT40 B lymphocytes. (A) Fura-2-loaded WTDT40 cells were incubated in nominally Ca²⁺-free medium and then exposed to 2 µM thapsigargin in order to deplete intracellular Ca²⁺ stores. After cytosolic Ca²⁺ returned to basal levels, Ba²⁺ (10 mM) was added to the medium. A representative trace from at least five independent experiments is shown. (B) Wild-type (WTDT40) or IP₃R-KO (broken line) DT40 cells were maintained in nominally Ca²⁺-free medium, exposed to 5 µg/ml anti-IgM antibody, and then Ba²⁺ (10 mM) was added where indicated. Representative traces from at least five independent experiments are shown.