PTN and breast cancer: We also defined 3 hair follicle-associated populations, outer bulge (OB, high Lhx2, Postn, Ptn), basal upper hair follicle cells (UHF-BC, high Apoe, Fst) and suprabasal upper hair follicle cells (UHF-SBC, high Krt17 and Krt79, Apoe) Fig. 2A–B, Supplementary File 3.