Interestingly, some genes known to be key players in cancer, here among MAP 3K1|MAP 2K4, NOTCH1|NOTCH3, PIK3CA, SYK, FOXP1, and TP53, were not retained in any co-expression module, e.g., they were encompassed by the gray portion in Additional file 9: Fig. S5. This evidence concerns the gene NOTCH1 and cancer.