ACTB and colorectal carcinoma: Among common reference genes used in PCR based gene expression CRC studies [28, 29], GAPDH was more frequently upregulated (log2 T/N > 0) in both HST and LST (Additional file 1: Figure S2b) while expression of ACTB was either up or downregulated (log2 T/N > 0 or < 0) in some LST and HST (Additional file 1: Figure S2c).