Fig. 1

Identification of the biological functions of ERK1/2 and ERK5 in TNBC. a Correlation analysis of MAPK3, MAPK1 expression with overall survival and MAPK7 expression with relapse-free survival of TNBC patients in TCGA database. b Immunoblotting analysis of protein levels of ERK5, p-ERK5, ERK1/2, p-ERK1/2 in MDA-MB-231 and MDA-MB-468 cells following treatment with BVD-523 (2.5, 5, 10 μM) for 24 h. c Immunoblotting analysis of protein levels of ERK5, p-ERK5, ERK1/2, p-ERK1/2 in MDA-MB-231 and MDA-MB-468 cells transfected with NC or ERK1/2 siRNA for 72 h. d Real-time qPCR of ERK1, ERK2, and ERK5 mRNA expression levels in cells transfected with NC or ERK1/2 siRNA for 48 h. e Immunoblotting analysis of protein levels of ERK5, p-ERK5, ERK1/2, p-ERK1/2 in MDA-MB-231 and MDA-MB-468 cells following treatment with XMD8-92 (2.5, 5, 10 μM) for 24 h. f Immunoblotting analysis of protein levels of ERK5, p-ERK5, ERK1/2, p-ERK1/2 in cells transfected with NC or ERK5 siRNA for 72 h. g Real-time qPCR of ERK1, ERK2, and ERK5 mRNA expression levels in MDA-MB-231 and MDA-MB-468 cells transfected with NC or ERK5 siRNA for 48 h. h Cell viability was determined by MTT assay after treatment with BVD-523 and XMD8-92 for 72 h at the indicated concentrations and ratios, and drug combination index of BVD-523 in combination with XMD8-92. i MTT assay was performed in cells transfected with ERK1/2, ERK5 and ERK1/2 + ERK5 siRNA, respectively, for 24 to 120 h. Data are presented as Mean ± SD. Compared to the Control group: ns, not significant; **p < 0.01, ***p < 0.001. Compared to the siERK1/2 group: ^###p < 0.001