SERPINB9 and skin squamous cell carcinoma: Higher DNA methylation of SERPINB9 in RTRs who developed cSCC vs. those who did not. Median DNA methylation of SERPINB9 was 58.7% (range: 32.5–81.3%) for region 1 and 54.4% (30.0–78.5%) for region 2 in patients with cSCC and 50.2% (21.8–77.5%) for region 1 and 46.4% (22.1–74.0%) for region 2 in the non-cSCC patients (region 1: p = 0.004 and region 2: p = 0.008).