Overexpression of CXCL1 and IL8 mRNA levels in human CRC development. a, b Box plots of CXCL1 (a) and IL8 (b) mRNA expressions in human mucosal tissues of normal colon (NC), normal liver (NL), colon adenoma (A), stages I-IV primary colorectal adenocarcinoma (I-IV), and CRC metastases to liver (Li) and lung (Lu). c Box plots of CXCL1 mRNA expressions in human primary CRC stratified according to TNM stages. d Box plots of IL8 mRNA expressions in human primary CRC stratified according to TNM stages. e Percentages of human colorectal malignant tissues with elevated CXCL1 mRNA expression occurred early in most human adenoma (A) and decreased slightly with cancer metastasis. f Percentages of human colorectal malignant tissues with elevated IL8 mRNA expression occurred predominantly at time of conversion from adenoma to stage I–II CRC and remained elevated with disease progression. “−” and “+” indicated normal mRNA levels and those that were three standard deviations above normal, respectively. SI represented arbitrary unit of signal intensity. Patient numbers (n) were as indicated.