CCL16 and endometriosis: To verify the results obtained from cDNA array experiments and to establish the variability between individuals, two candidate genes (CCL16 and CCL21, also known as HCC-4 and 6C-kine respectively) that had not previously been identified as associated with endometriosis, were selected for further analysis using quantitative real-time RT-PCR on individual unamplified RNA samples of glands from eutopic tissue (patients and controls: n = 3 subjects per cohort).