Table 1. Classification of proteins in the IFM and FM of young and old tendons.

		Young IFM	Young FM	Old IFM	Old FM
ECM Proteins	Total Protein Number	130	92	123	89
	Collagens	16 (12.3%)	15 (16.3%)	14 (11.4%)	13 (14.6%)
	Glycoproteins	13 (10%)	8 (8.7%)	15 (12.2%)	8 (9.0%)
	Proteoglycans	8 (6.2%)	7 (7.6%)	9 (7.3%)	6 (6.7%)
	ECM regulators	4 (3.1%)	2 (2.2%)	1 (0.8%)	8 (9.0%)
	ECM-affiliated	3 (2.3%)	1 (1.1%)	4 (3.3%)	2 (2.2%)
	Secreted factors	2 (1.5%)	1 (1.1%)	2 (1.6%)	0
	Total	47 (36.2%)	34 (37.0%)	45 (36.6%)	37 (41.6%)
Non-ECM proteins	Cytoskeletal	36 (27.7%)	24 (26.1%)	41 (33.3%)	26 (29.2%)
	Histones	9 (6.9%)	22 (23.9%)	3 (2.4%)	4 (4.5%)
	Cell Membrane	5 (3.8%)	2 (2.2%)	4 (3.3%)	1 (1.1%)
	Enzymes	16 (12.3%)	2 (2.2%)	8 (6.7%)	6 (6.7%)
	Transcription/translation	7 (5.3%)	1 (1.1%)	2 (1.6%)	1 (1.1%)
	Other/Unknown	10 (7.7%)	5 (5.4%)	20 (16.2%)	10 (11.2%)
	Total	83 (63.8%)	58 (63.0%)	78 (63.4%)	52 (58.4%)

Proteins were classified using MatrisomeDB and PANTHER classification systems. Numbers in brackets indicate percentage of total protein number.