Complex sentence: J2 once had his own series, which lasted for twelve issues, and has made a few appearances in "Spider-Girl" (also set in the MC2 universe, starring the daughter of Spider-Man).
Split into simpler sentences: J2 once had his own series, which lasted for twelve issues. He has made a few appearances in "Spider-Girl" (also set in the MC2 universe, starring the daughter of Spider-Man).