E2

E2, e2, E02, E.II, e² or E-2 may refer to:; in biology or medecine:
* E2 regulatory sequence for the insulin gene
* Prostaglandin E2 receptor, a human gene
* E02 : Subclinical iodine-deficiency hypothyroidism ICD-10 code
* Oestradiol
* Dihydrolipoyl transacetylase, the second element of the multienzyme pyruvate dehydrogenase complex

; in technology :
* E2 (cipher), a block cipher submitted to the AES competition by NTT
* E2 reaction, a type of organic reaction
* Honda E2, one of the predecessors of Honda's ASIMO robot
* Motorola ROKR E2, a smartphone
* Tungsten E2, a business-class Palm OS-based handheld computer
* Shure E2 (sometimes called E2c) canalphones
* Everything2, a collaborative web-based community consisting of a database of interlinked user-submitted written material

In Entertainment:
* Design e2, a documentary television series broadcast by PBS
* "E²", an episode of "Star Trek: Enterprise"
* MTV e2, a Canadian entertainment news program that airs on MTV Canada
* E2 (TV channel), a Turkish TV channel
* e2 by SKY PerfecTV!, a satellite television service in Japan operated by SKY Perfect
* E² (album), a 2007 album by Eros Ramazzotti

In transportation:
* E2 (Zimbabwe), a road in Zimbabwe
* E-2 Hawkeye, a carrier-based AWACS aircraft of the United States Navy
* E2 Series Shinkansen, a Japanese high-speed train
* EMD E2, an early American passenger-train diesel locomotive
* European walking route E2, a long-distance footpath that runs from Galway in Ireland to France's Mediterranean coast
* Fokker E.II, a 1915 German single-seat monoplane fighter aircraft
* HMS "E2", an E-class submarine of the Royal Navy
* Kampuchea Airlines IATA code
* LB&SCR E2 Class, a class of 0-6-0T steam locomotives designed by Lawson Billington
* London Buses route E2
* Pfalz E.II, a German aircraft powered by the Oberursel U.I engine
* PRR E2, an American
* Taylor E-2, a small, light and simple utility aircraft
* USS "E-2" (SS-25), an E-class submarine of the United States Navy
* WLWR Class E2, a Waterford, Limerick and Western Railway Irish steam locomotiveand also :
* North-South Expressway Southern Route, a Malaysia Highway

In other fields:

* E-2 South Korean visa, a South Korean language teaching visa
* London E2, the postcode for Bethnal Green in London
* Private E-2, the paygrade of the rank Private in the U.S. Army
* E2 (nightclub), a nightclub in Chicago
* an abbreviation for the second Eternity puzzle