Question: What occupation is shared by Luca Prodan and Glenn Gregory?

Context paragraphs:
Naked as Advertised: Naked as Advertised is the eighth studio album by the English synthpop band Heaven 17.  It was originally released in 2008, on the label Just Music, three years after their previous album, "Before After".  The album contained re-workings of tracks such as "Temptation" along with versions of Martyn Ware songs best known from his time with the Human League, including "Being Boiled" and "Empire State Human", as well as a cover of The Associates' hit "Party Fears Two".  Following the departure of Ian Craig Marsh in 2007, this is the first Heaven 17 album with the band consisting of the duo of Glenn Gregory and Ware.

Glenn Gregory: Glenn Peter Gregory (born 16 May 1958) is an English singer, songwriter, and multi-instrumentalist whose music career spans more than 30 years.  He came to prominence in the early 1980s as co-founder and lead singer of the new wave and synthpop band Heaven 17, which released six singles that entered the Top 40 charts in the United Kingdom during the 1980s, and 1990s, including "Temptation", "Come Live with Me", "Crushed by the Wheels of Industry", "Sunset Now", "This Is Mine", and "(We Don't Need This) Fascist Groove Thang" .

Mark Tinley: Mark Ty-Wharton (born Mark Tinley; 18 March 1963) is a British music technologist, informal logician and public speaker who specialises in presentations using sound art.  He is best known for his work as a guitarist, programmer, sound engineer and record producer with Adamski, Duran Duran, TV Mania, Gary Numan, Glenn Gregory, The Dandy Warhols and others.

Las Pelotas: Las Pelotas (in English: "The Balls"); is an Argentine band rock and reggae, from Córdoba.  This band was formed after the separation of Sumo, due to the death of their singer, Luca Prodan in 1987.  The group currently consists of vocalist and guitarist, Germán Daffunchio, Gabriela Martínez on bass, Tomás Sussman on guitar, Sebastián Schachtel on Keyboards and Gustavo Jove on drums.  Their original vocalist, Alejandro Sokol, was part of the band from 1988 to 2008; year that begins his solo career, cut short by his sudden death in 2009.

Luca Prodan: Luca Prodan (17 May 1953 – 22 December 1987) was an Italian–Scotish musician and singer.  He was the leader and singer of Sumo, one of the most influential rock bands of Argentina, and is widely considered as one of the most important artists of the last quarter of the twentieth century in his country.

Sumo (band): Sumo was a 1980s Argentine alternative rock band, merging "post-punk" with "reggae".  Headed by Italian-born Luca Prodan, it remained underground for most of its short activity, but was extremely influential in shaping contemporary Argentine rock.  Sumo introduced British post-punk to the Argentine scene, with many lyrics in English.  And provided a visceral counterpoint to the progressive and nueva canción influences then dominant in "Rock en Español".

Andrea Prodan: Andrea Prodan (born 16 November 1961) Scottish-Italian film actor, composer and musician is the younger brother of Argentine rock star Luca Prodan.  The Prodan family, after suffering internment in a Japanese concentration camp during WW II, was expelled from China due to Mao.  Andrea's Italian father was an author and talented sportsman, and had run a prosperous business, with expertise in ancient Chinese pottery.  His mother is Scottish.

British Electric Foundation: B.E.F. (British Electric Foundation) was a band/production company formed by former Human League members Martyn Ware and Ian Craig Marsh, which became largely eclipsed by its best-known project Heaven 17 (with lead singer Glenn Gregory).

Divididos: Divididos ("Divided") is an Argentine rock band.  The band was formed in 1988 after the death of Luca Prodan and the consequent dissolution of the band Sumo.  Ricardo Mollo (vocals, guitar) and Diego Arnedo (bass guitar) joined drummer Gustavo Collado to form a band named "La División" (The Division), which would be later called "Divididos".

Heaven 17: Heaven 17 are an English new wave and synth-pop band that formed in Sheffield in 1980.  The band were a trio for most of their career, composed of Martyn Ware (keyboards), Ian Craig Marsh (keyboards) (both previously of the Human League) and Glenn Gregory (vocals).  Although most of the band's music was recorded in the 1980s, they have occasionally reformed to record and perform, playing their first ever live concerts in 1997.  Marsh left the band in 2007 and Ware and Gregory continued to perform as Heaven 17.

Supporting paragraphs: Luca Prodan Glenn Gregory
Answer: singer