Cleavage Furrow initiated by 'in position' signal ?

According to the HHMI DVD Life Matrix (lecture 2), the formation of the 'Cleavage Furrow', during cell division, is implemented, by myocin-2 & anillin proteins, which cluster around the middle of the as-yet-undivided cell, even as the chromosomes are pulled to opposite poles. The lecturer, Dr. Stuart Schreiber, seemed to say, that no-one as yet knows what triggers the Cleavage Furrow to form, or pinch off.

And yet, Dr. Schreiber showed, that 'Small Molecules' can bind to Proteins, activating or de-activating them. Could it be, that once the chromosomes are in position, they send out some sort of 'we're in position, sir' signal ?? That chemical signal, then, could hypothetically activate the cytoskeleton proteins, to start the Cleavage Furrow forming, and fissioning.