Some research scientists at UCLA found a big difference between lactate levels in mouse skin between hairless mice and mice with hair, particularly inside the Hair Follicle Stem Cells (HFSCs). The HFSCs in the hairy mice were activated; the ones in the hairless mice were dormant.
When you ingest food that contains glucose (simple sugar), it gets broken down in the body's metabolic cycle and changed to other molecules. Some of it becomes pyruvate which goes to the mitochondria -- little mini-organs inside your cells -- and from there it makes energy for the cells (like, for your muscles). Another thing that can happen to the pyruvate molecule is, it doesn't go to the mitochondria for energy production, but instead it can be converted into lactate. (Lactate is the same chemical that builds up in your muscles after strenuous exercise and makes them feel tired.)
If the HFSCs have a lot of lactate in them, apparently they become activated and start making hair. If they have low levels of lactate, or no lactate, they become dormant and do nothing -- at least that's what the UCLA scientists found in their study. This is analogous with what they think happens in balding people.
If you add this drug, UK5099 (or the other drug they found), by applying it topically, perhaps it will increase lactate levels in the HFSCs, and revive the miniaturized follicles in people with MPB.