ITPR1 and small cell lung carcinoma: Our earlier work indicates that BIRD-2-mediated disruption of Bcl-2–IP3R interaction induces marked, lethal elevation of cytoplasmic Ca2+ concentration in Bcl-2-positive lymphoid malignancies.26, 29, 32, 35 BIRD-2 similarly induces a striking elevation of cytoplasmic Ca2+ in SCLC cells (Figure 5a), which is not observed in cells treated with Scr control peptide (Figure 5b).