Why is After School's Lizzy absent from "Running Man"?

After six months of airing, SBS's "Running Man" seems to have finally carved a place in the variety show world by consistently recording 10~15% in viewer ratings. While fans have been immensely enjoying the antics of the cast, many have been wondering why After School's Lizzy has been absent from the show. Lizzy first joined the cast in October of 2010, but viewers haven't been able to see her since January.�Jo Hyo Jin PD spoke to Newsen on February 7th and revealed, "Lizzy appeared on the program as a long-term guest.�She's done well for our show over the past few months, and we still keep in contact. She is still considered a part of the 'Running Man' family." Lizzy is said to be focusing on After School's Japanese advancement this year, which explains her absence from the show.�Jo PD continued, "Lizzy can join 'Running Man' whenever she wants." Source: Newsen via Nate