Table 3. Gene ontology of transcripts correlated with stiffness.

Gene Ontology	Observed	Expected	p-value
Biological Process (selection from 21)	Positive Bundle Stiffness Correlation
extracellular matrix organization	13	2.25	5.54E-06
collagen fibril organization	8	1.07	7.53E-05
collagen biosynthetic process	5	0.54	1.40E-03
Molecular Function (selection from 5)
extracellular matrix structural constituent	12	2.25	2.58E-05
growth factor binding	8	2.25	2.56E-02
proteoglycan binding	3	0.32	2.60E-02
Cellular Component (selection from 10)
proteinaceous extracellular matrix	22	5.46	1.65E-07
fibrillar collagen	6	0.75	2.00E-04
basement membrane	8	1.93	4.70E-03
Cellular Component	Negative Bundle Stiffness Correlation
mitochondrial intermembrane space	4	0.36	6.70E-03
organelle envelope lumen	4	0.43	1.00E-02
Biological Process (selection from 20)	Negative Fiber Stiffness Correlation
ubiquitin-dependent protein catabolic process	7	1.34	2.54E-02
cellular protein catabolic process	9	2.89	3.18E-02
proteasomal protein catabolic process	4	0.60	3.81E-02
Cellular Component (selection from 9)
nucleus	28	16.61	1.44E-02
proteasome complex	4	0.48	2.16E-02
membrane-bounded organelle	35	25.73	2.76E-02

Gene ontologies that were over-represented among genes that had a significant correlation (p<0.05) with either fiber or fiber bundle passive stiffness measurements. (Category) is the number of genes on the reference list or in this case significantly altered in CP. (Observed) is the number of genes significantly correlated with mechanical stiffness that fall into the category. (Expected) is the number of genes expected to be in the significantly altered list based on the relative sizes of lists.