A deeper insight on the molecular mechanism revealed that Jak-Sat signaling participated in and promoted a feedback loop in aged Krt-15-GFP-positive stem cells (one of the best-charaterized stem cell in skin) in response to pro-inflammatory environment with increased levels of protein cytokines (such as BLC/CXCL13, GM-CSF, ICAM-1/CD54, IL-1α), proving that age-related inflammation may inhibit the function of epidermal stem cells [45]. This evidence concerns the gene CXCL13 and age.