Fig. 3: Biochemical analysis of ERK5 expression in patient samples and its relationship to patient survival.

a ERK5 protein expression was analyzed in a cohort of patients from the University Hospital of Salamanca diagnosed with different sarcoma subtypes. One milligram of tumor protein was subjected to immunoprecipitation with the anti-ERK5 Pro1 antibody followed by Western blot analysis with the anti-ERK5 C-terminal antibody. The number above each lane indicates the tissue bank classification. N nontumor tissue, T tumor tissue. Calnexin was used as a loading control. b A total of 0.5 mg of tumor protein extract was subjected to immunoprecipitation and analysis as described above. The red arrow points to a possible truncated variant of ERK5. Calnexin was used as a loading control. c Box plot showing the expression level of ERK5 (a.u.) in 69 samples obtained from patients of the University Hospital of Salamanca. The Western blot shown in Fig. 3a was used for quantification of ERK5 band densities using ImageLab software. ERK5 signal expression was normalized to the signal expression of an internal sample used as a control. *p ≤ 0.05; ***p ≤ 0.001; (red asterisk), p = 0.0539. d Box plots showing the ERK5 expression level (a.u.) in each subtype of tumor vs. the corresponding normal tissue. e Kaplan–Meier overall survival analysis of sarcoma patients from the University Hospital of Salamanca with available clinical data (n = 55) for 220 months of follow-up stratified by ERK5 protein expression. The lower tertile of expression was set as the cutoff threshold to sort patients into the low/high ERK5 expression groups.