Fig. 3.

Egr-1 and CREB were involved in cisplatin resistance mediated by CTSL. a Western blot was conducted to measure the expression level of Egr-1 and CREB in A549, A549/TAX and A549/DDP cells. b Silence of Egr-1 in A549/DDP cells by transfecting Egr-1 siRNA, and then western blot was used to detect the expression level of Egr-1 and CTSL. d and e CCK8 and flow cytometry assay were conducted to determine the change of cisplatin resistance in A549/DDP cells transfected with Egr-1 siRNAs and the control. c Western blot was adopted to detect the expression of CREB of A549/DDP cells transfected with CREB siRNAs and the control. f and g CCK8 and flow cytometry assay were performed to determine the change of cisplatin resistance of CREB-silenced A549/DDP . h Luciferase assay was used to detect CTSL promoter activity in A549 and A549/DDP cells. i Luciferase assay was performed to detect CTSL promoter activity in A549/DDP cells transfected with CREB siRNAs and the control. At least three independent experiments were performed. *P < 0.05, **P < 0.01 and ***P < 0.001 compared with control