Since both machine learning and differential gene expression analysis suggest CNGB1 as a marker of non-response to NAC, we next validated its expression using a tissue microarray comprising tumours from the 30 MIBC patients treated with NAC used in the gene expression profiling analysis (Discovery cohort); thus, acting as an internal validation on a protein level of the Discovery cohort (Figure 4a). This evidence concerns the gene CNGB1 and neoplasm.