P2RX3 and endometriosis: Measurement of mRNAs encoded by TAC1 and nociceptive ion channels revealed differences between tissue samples; TAC1 was elevated only in endometriosis lesions (Figure 1A; P < .05), and P2RX3 was increased in the peritoneum of women with CPP, regardless of whether they were diagnosed with endometriosis compared with the peritoneum of healthy women (Figure 1B; P < .05).