The team also used their simulation to predict what would happen if they removed each of the partners from the dance. If they took out Bmp, Sox9 activity also died away and the fingers didn’t form at all; instead, the virtual limb bud continued growing as a shapeless lump. If they took out Wnt, Sox9 became active everywhere and the spaces between the fingers disappeared. If they blocked Bmp and Wnt together, these effects partly cancelled each other out but the number of fingers decreased.
The team then checked these predictions by applying drugs that block Wnt and Bmp to isolated limb buds growing in Petri dishes. In every case, the reality matched the predictions.
Nice case study in evo-devo, with a clear importance given the widespread nature of these gene systems.