(a,d) Two subset no. 2 CLL-derived clonotypic BcR IGs (P11475, BCR17) were expressed in TKO cells reconstituted with a OHT-inducible variant of SLP-65 (ERT2-SLP65). The IG surface expression is shown. (b,e) Intracellular Ca2+ influx on induction of SLP65 function with OHT. The Arg110LGly (R100G), Asp50LAla/Asp52LAla (D50A/D52A) and Lys16LAla (K16A) mutants of both receptors did not signal on OHT addition. A control mutation (Arg19LAla) did not affect Ca2+ influx. (c,f) When crosslinked with an anti-λ-chain antibody, both receptors induced Ca2+ influx. In all panels showing Ca2+ influx measurements, addition of OHT is indicated by black arrows.