up on something, be
Be well informed or up-to-date about something, as in I'm not up on the latest models of cars. [Colloquial]
Words nearby up on something, be
up close and personal,
up for grabs,
up front,
up in arms,
up in the air,
up on something, be,
up one's alley,
up one's sleeve,
up quark,
up the creek,
up the river