CDKN2A and idiopathic pulmonary fibrosis: We applied this technique to segregate CTFR-hi and CTFR-lo fibroblasts from IPF lungs (from patients undergoing lung transplantation), and qPCR demonstrated significant enrichment of p16INK4a expression in the CTFR-hi population (but not p14ARF encoded in the same locus) along with other pathologic fibroblast markers such as p21, CTHRC1, HAS1, and PostN (Figure 6F, Supplemental Figure 7D).