Kallikrein 1 and 6

Immunoblotting was performed as previously described^{30 (link)}. Equal amounts of cellular protein or tissue lysates were used. Blots were incubated with specific antibodies to elastase 1 (200ng/ml; Santa Cruz Biotechnology), elastase 2 (200 ng/ml; Abgent), kallikrein 1 and 6 (both 200 ng/ml; Sigma-Aldrich), kallikrein 5 (300 ng/ml; Acris Antibodies), c-kit (200 ng/ml; Cell Signaling Technology), Sca1 (200 ng/ml; Merck Millipore), CD10 (1:100; ThermoFisher), CD44 and CD90 (both 200 ng/ml; Abcam), CD71 (1:200; ThermoFisher), pSMAD1/5/8 (200ng/ml; Santa Cruz Biotechnology), Sox2, Klf4, Slug and pSMAD2/3 (all 400 ng/ml; Cell Signaling Technology) and total SMAD (400 ng/ml; Santa Cruz Biotechnology). β-Actin (1:5000 dilution; Sigma-Aldrich) was used as loading control.

Tissue sections were fixed in 4% paraformaldehyde and processed as previously described^{31 (link)}. Immunofluorescence was performed as previously described^{11 (link)}. We used specific antibodies for CD31 (Merck Millipore), vWF (Dako), Cbfa1, Osterix and elastase 1 (all from Santa Cruz Biotechnology), elastase 2 (Abgent), kallikrein 1 and 6 (Sigma-Aldrich), kallikrein 5 (Acris Antibodies), Sox2, Klf4, c-kit, Slug (all from Cell Signaling Technology), Sca1 (Merck Millipore), CD10 and CD71 (both from ThermoFisher), N-cadherin (Life technology), CD44 and CD90 (both from Abcam). Nuclei were stained with 4',6-diamidino-2-phenylindole (DAPI, Sigma-Aldrich).