IHC staining shows localization of RECQ helicases in normal colonic mucosa and CRC. All of the RECQ helicases were detected in the nucleus in both normal colonic mucosa and CRCs. Allred scores for each of the RECQ helicases from IHC of TMAs are also presented. Low expression of RECQL5 in tumors compared to normal mucosa can be seen (P = .0031, Wilcoxon signed rank test), which is consistent with the results obtained from the RECQL5 qRT-PCR assays. WRN showed higher expression in tumors compared to normal colon mucosa (P = .0128, Mann-Whitney), suggesting that immunostaining scores and mRNA expression levels of WRN do not correlate. The other RECQ helicases also show statistically significant differences in expression between tumor and normal tissue (BLM, P = .0046, Wilcoxon signed rank test; RECQL, P = .0287, Wilcoxon signed rank test; RECQL4, P = .0103, Wilcoxon signed rank test); however, this difference likely does not translate to clinical significance. Allred scores for the selected matched tumor normal images chosen to show localization are given as follows: WRN: N =7, T =0; BLM: N =7.75, T =7; RECQL: N = 7.25, T =6; RECQL4: N =7, T =8; RECQL5: N = 6 (cytoplasmic 2), T = 0 (cytoplasmic 2). All images were photographed at x20. Asterisks indicate statistical significance between the two groups identified.