According to the study it only increases IGF-1, but it may have other effects that are not known about.  Red Clover flowers contain p-Coumaric Acid.  I could only find p-coumaric acid available for scientific use.

p-Coumaric acid stimulates longitudinal bone growth through increasing the serum production and expression levels of insulin-like growth factor 1 in rats.

“The aim of the present study was to examine the effects of p-coumaric acid on the longitudinal growth of the long bone in adolescent male rats. Teatment with p-coumaric acid significantly increased the tibial length and the height of each growth plate zone and the ratio of 5-bromo-2′-deoxyuridine-positive cells relative to total proliferative cells. Expression of insulin-like growth factor 1 and its receptor in the proliferative and hypertrophic zones, and serum levels of growth hormone and insulin-like growth factor 1 were significantly increased as well in the p-coumaric acid-treated group. Via increasing both the serum level of insulin-like growth factor 1 and its expression, p-coumaric acid could promote cell proliferation in growth plate zones. These results suggest that p-coumaric acid has the potential to increase height and may be a feasible alternative to growth hormone therapy.“<-the statement that this may be a feasible alternative to growth hormone therapy makes this seem more powerful than just your typical supplement.

The study also mentions other supplements that have beneficial effects on chondrogenesis.  If you look at figure 1 and 2 you can see that there are differences between p-Coumaric Acid and Growth Hormone growth plates.  The scientists suggest that p-Coumaric acid upregulates IGF-1 and IGF-1R.