Table 2. Classification of differentially abundant proteins (identified using ≥ 2 peptides) in the IFM compared to the FM of young tendon.

		Higher in Young IFM	Higher in Young FM
ECM Proteins	Total Protein Number	48	12
	Collagens	1 (2.1%)	3 (25.0%)
	Glycoproteins	5 (10.4%)	5 (41.7%)
	Proteoglycans	1 (2.1%)	1 (8.3%)
	ECM regulators	0	1 (8.3%)
	ECM-affiliated	2 (4.2%)	0
	Secreted factors	0	0
	Total	9 (18.8%)	10 (83.3%)
Non-ECM proteins	Cytoskeletal	19 (39.6%)	1 (8.3%)
	Histones	6 (12.5%)	0
	Cell Membrane	0	0
	Enzymes	5 (10.4%)	0
	Transcription/translation	2 (4.2%)	0
	Other/Unknown	7 (14.6%)	1 (8.3%)
	Total	39 (81.2%)	2 (16.6%)

Numbers in brackets indicate percentage of total protein number. A full list of differentially abundant proteins is available in Supplementary Table 3.