It was hypothesized that part of the reason that treatment with an FTI such as alendronate is inefficient is due to prenylation by geranylgeranyltransferase. Since statins inhibit geranylgeranyltransferase, the combination of an FTI and statins was tried, and markedly improved "the aging-like phenotypes of mice deficient in the metalloproteinase Zmpste24, including growth retardation, loss of weight, lipodystrophy, hair loss, and bone defects".[55]