somatotropin

The story

1. Proto-Indo-European*tewh₂-
2. Proto-Indo-European*twoH-mn̥
3. Proto-Hellenic*twṓmə?
4. Proto-Indo-European*styeH-
5. Proto-Indo-European*(s)tyoH-mn̥
6. Proto-Hellenic*styṓmə?
7. Ancient Greekσῶμᾰ (sômă)
8. Englishsomato-
9. Proto-Indo-European*trep-
10. Ancient Greekτρέπω (trépō)
11. Ancient Greekτροπή (tropḗ)
12. Ancient Greekτροπῐκός (tropĭkós)
13. English todaysomatotropin

From somato- + -tropin.