Fig. 2. DAG and downstream effectors involved in the regulation of SRF and NFAT downstream of the BCR. (A) DAG plays a role in the regulation of SRF via BCR signaling pathway. SRF transcriptional activity was determined in WT or IP₃R^–/– DT40 cells pre-treated with the indicated concentrations of calphostin C prior to no stimulation or stimulation with anti-IgM for 6 h. (B) Partial requirement for PKC. SRF and NFAT transcriptional activity was determined in WT DT40 cells pre-treated with the indicated concentrations of the pan-PKC inhibitor Gö6976 prior to BCR stimulation. (C) Partial requirement for Ras and Rap1. SRF and NFAT transcriptional activity was determined in WT DT40 cells transfected with 20 µg empty vector (control), dominant negative Ras (N17) or dominant negative Rap1 (N17). *P < 0.05 versus vector transfected control. (D) Full requirement for the MEK–ERK pathway. SRF, NFAT and SRE transitional activity was determined in WT DT40 cells pre-treated with the indicated concentrations of the MEK inhibitor PD98059 prior to BCR stimulation. (E) Differential requirement for JNK activity. SRF and NFAT transcriptional activity was determined in WT DT40 cells pre-treated with the indicated concentrations of the JNK inhibitor SP600125 prior to BCR stimulation.