Bacillus thuringensis Berliner Cry1A toxins are three-domain proteins that show insecticidal activity to certain important lepidopteran insect pests. Transgenic plants, Bt-maize, Zea mays L.; or Bt-cotton, Gossypium hirsutum L.; expressing Cry1Ab or Cry1Ac toxins have been planted worldwide and are efficient in insect control. Here, we revise recent data on the mode of action of Cry1Ab toxin. After activation by proteases in the midgut, Cry1Ab toxin binds to the more abundant but low affinity glicosylphophatidylinositol (GPI)-anchored proteins alkaline phosphatase or aminopeptidase-N (ALP and APN, respectively) through domain II loop 3 and domain III ß16. This binding event concentrates the toxin in the microvilli membrane where it then binds to Cadherin receptor with high affinity. After binding to Cadherin, an extra proteolytical cleavage is produced and oligomers are formed. Oligomers gain a 200 higher binding affinity to both GPI-anchored proteins through domain II loop 2. The binding of Cry1Ab oligomers to GPI-anchored proteins facilitates insertion into the membrane and pore formation. This binding mechanism was named ping-pong because it involves going from GPI-anchored proteins to Cadherin and back to GPI-anchored proteins before membrane insertion. We also show the ALP receptor has a greater role in toxicity than does APN.