Fig. 7

Immunohistochemistry analysis of TK1 expression in colon cancer tissue. Colon cancer tissue arrays were stained with anti-TK1 antibody ab91651, GAPDH, or isotype antibody. GAPDH was used as a positive control to account for housekeeping gene expression. The isotype antibody was used to account for background noise and non-specific binding. Tissues were imaged in a light microscope at 20×. Analysis was conducted using a gray scale. The lower the gray value, the darker the staining. a Quantitative analysis of colorectal cancer IHC staining. The top graph shows that there is a statistically significant expression of TK1 in ~ 74% of the colon adenocarcinoma tissues. The bottom graph shows the TK1 expression next to GAPDH and isotype controls. Background levels show no statistical difference between malignant and normal healthy tissues. Malignant and normal healthy tissue showed non-statistical difference in GAPDH expression, whereas TK1 expression did show a statically significant difference between TK1+ and TK1− tissues. b Image showing colorectal adenocarcinoma positive for TK1. The yellow circle encloses an atypical glandular structure positive for TK1 in over 90% of the cells. c Image showing colorectal adenocarcinoma negative for TK1. The circle an atypical glandular structure negative for TK1. Overall, the tissues shown in (b, c) show what we observed in the tissue’s average gray values represented in a, that some colorectal adenocarcinoma tissues showed strong TK1 staining and some showed negative TK1 staining. ***P ≤ 0.001; ns = P > 0.05