(a): bcd inquires whether it is possible to bind Bcd to the 5’ upstream region of hb.
(b): hb responds that the Bcd binding to its 5’ upstream region is possible.
(c): Bcd is supplied to the 5’ upstream region of hb.
(d): hb responds that Bcd has started binding to the 5’ upstream region.
(e): bcd continues to supply Bcd to the 5’ upstream region of hb.
(f): hb responds that Bcd binding has been completed.
(g): bcd stops supplying Bcd to hb.
