NK603 X MON810 (OECD identifier: MON-ØØ6Ø3-6 x MON-ØØ81Ø-6) maize is an F1 hybrid resulting from the hybridization of the herbicide-tolerant maize inbred NK603 (MON-ØØ6Ø3-6) with the insect-resistant maize inbred MON 810 (MON-ØØ81Ø-6). This stacked maize hybrid is a product of traditional plant breeding, and therefore is not automatically subject to regulation in all jurisdictions as are transgenic plants resulting from recombinant DNA technologies. Certain jurisdictions may request notification in advance of the release of a stacked hybrid, or may request information to conduct an environmental and food safety assessment.  Examples of jurisdictions that require either notification or information about stacked hybrids prior to their release into the environment, and for use in human food and livestock feed are Canada and Japan.<br> <br>The stacked hybrid NK603 X MON810 expresses two novel proteins:  CP4 EPSPS which confers tolerance to the herbicide glyphosate, and the delta-endotoxin Cry1Ab which confers resistance to the European Corn Borer and other lepidopterans.  The CP4 EPSPS protein is produced by the <i>cp4 epsps</i> gene from NK603, and the insecticidal protein Cry1Ab, by the <i>cry</i>1Ab gene from MON810.  The novel traits of each parent line have been combined, through traditional plant breeding, to produce this new hybrid.  For a full description of each parent line please refer to the individual product descriptions in the crop database for <a href="dbase.php?action=ShowProd&data=NK603&frmat=LONG"><b>NK603</b></a> and <a href="dbase.php?action=ShowProd&data=MON810&frmat=LONG"><b>MON810</b></a>.<br>The inserted genes and their gene products have a history of safe use, and have undergone review and approval by several regulatory agencies.  No interactions among the gene products or negative synergistic effects are expected in the stacked hybrid.  The Cry1Ab protein is not an enzyme and therefore does not affect plant metabolism.  The CP4 EPSPS has high affinity for its substrates phosphoenolpyruvate (PEP) and shikimate-3-phosphate, which are part of the shikimate metabolic pathway.   CP4 EPSPS and Cry1Ab are therefore not expected to interact within, nor affect the metabolism of the stacked hybrid.  <br>Studies were conducted to compare the resistance to lepidopterans and tolerance to glyphosate between the stacked cotton line and each parental line.  There were no significant differences in the resistance to the lepidopteran pests, or in the tolerance to applications of glyphosate in the stacked line, compared to the parental lines.