Relative mRNA expression of KCNB1 and KCNA5 in tissues from patients with GC and CRC, determined by quantitative PCR. Histograms show mRNA levels of KCNB1 (a) and KCNA5 (b) genes in 35 tumour tissues compared with their surrounding peritumoral tissues from patients with GC and CRC, expressed with the 2-ΔCT method. P-values are based on the Mann–Whitney U-test (*p < 0.05). c The histogram shows the copy number variations of the KCNB1 and KCNA5 genes in tumour tissues from GC (n = 19) and CRC (n = 16) patients, expressed with the 2-ΔCT method. Vertical bar graphs represent the means and the error bars represent the standard deviation calculated for each group. d Correlation between relative gene expression of KCNB1 and KCNA5 within CRC and GC samples (tumour and peritumoral tissue). Spearman rank correlation (r) and p values are indicated.