Osmosis Jones

Frank Detomello is a slovenly zookeeper, and simple father to the only young and bright girl named Shane, who catches a cold right after when he swallowed a germ-ridden egg! The inside of his body is known as the "City of Frank". An unlikely hero of a policeman white blood cell, by the name of Osmosis Jones works as a member of Immunity, for Frank's immune system, as a white blood cell. But with that germ-ridden egg comes a mortal danger: Osmosis discovers Frank has really contracted a villainous and black-hearted deadly virus known as Thrax who arrives and plotting to ultimately overheat Frank's body, killing him from the inside out! Thrax is motivated by trying to become the nastiest new virus, attempting to kill each new victim faster than the previous. His grandiose plan for Frank is death in 48 hours, breaking previous medical records! Meanwhile the pill that Frank took, Drix arrives in the body and covers Frank's throat with ice to cover the irritation. Osmosis Jones becomes his newest partner. Now it's all up to only Osmosis and Drix to put an end of Thrax's plans before Frank gets sick forever and Shane will become an orphan!

Osmosis Jones (also known as Ozzy & Drix: The Fantastic Voyage Adventures of Osmosis Jones) (2001) is a live-action/animated film whose title character is Osmosis Jones, an anthropomorphic white blood cell. Unusual for this genre, the live action characters and cartoon characters never meet. The live action characters are people as they appear in the real world, and the animated characters are the cells and germs which live inside a man named Frank, whom the story concerns. It spawned a Saturday morning cartoon spinoff, Ozzy & Drix, which aired on Kids WB from 2002 to 2004, and featured Osmosis Jones and his friend Drix inside a new body.

Source: Wikipedia