Table 1. Properties and function of soluble signals involved in endochondral ossification.

Soluble Signal	Molecular weight (Da)	Biological function	Typical concentration in cell culture	Calculated isoelectric point (IP)
WNT agonist	350	Synthetic agonist on the Wnt pathway [36]	0.25 μg/ml
Purmorphamine	521	Synthetic agonist on the Hh pathway [37–39]	0.5 μg/ml
rhWNT3A	37,400	Acting on the Wnt pathway [40,41]	5–200 ng/ml	8.46
rhFGF2	16,400	Inhibits chondrocyte proliferation and facilitates hypertrophy during EO [42]	1–10 ng/ml	9.59
rhVEGF	19,000	Permits vascularization of cartilage [43]	1–10 ng/ml	9.01
rhBMP4	13,100	Acting on the TGF-ß pathway and acts during bone formation [44,45]	1–50 ng/ml	7.60