Fig. 6

Immunohistochemistry analysis of TK1 expression in breast cancer tissue. Breast 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 breast cancer IHC staining. The top graph shows that there is a statistically significant expression of TK1 in 20% of the ductal carcinoma 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 breast ductal carcinoma positive for TK1. The yellow circle encloses a malignant gland structure corresponding to a moderately differentiated ductal carcinoma, and the arrow shows strong nuclear staining against TK1 in approximately 25% of the cells. c Image showing breast ductal carcinoma negative for TK1. The green circle shows an atypical gland structure corresponding to moderately differentiated ductal carcinoma negative for staining against TK1. The green arrow shows the tumor stroma conformed by fibrotic tissue also negative for TK1. Overall, the tissues shown in Fig. 5b, c show what we observed in the tissue’s average gray values represented in Fig. 5a, that some ductal carcinoma showed strong TK1 staining and some showed negative TK1 staining. ***P ≤ 0.001; ns = P > 0.05