Figure 5. BAPTA-AM exposures at high doses cause increased clusterin (CLU) promoter activities. 1403 MCF-7 cells were pre-loaded with vehicle alone (0.1% dimethylsulfoxide (DMSO)) or with BAPTA-AM in vehicle for 30 min, and then mock irradiated or exposed to 5 Gy ionising radiation (IR). CLU promoter activity was then assessed by standard luminometer readings as described in the Materials and Methods section. Experiments were performed three times in triplicate, and statistical analyses of the data were performed using the Student's t-test. At high doses, BAPTA-AM can cause Ca²⁺ influx and induce CLU promoter activity to a level statistically equivalent to 5 Gy IR. High dose BAPTA-AM exposures also resulted in increases in endogenous CLU protein responses (not shown).