POWER OF ATTORNEY
                 (For executing Forms 3, 4 and 5 under Rule 16)



         KNOW ALL BY  THESE  PRESENTS,  That the  undersigned  hereby
constitutes  and  appoints  F.  Dean  Copeland,  Susan N.  Roth,
Christopher A. Parrott, or Jo C. Dearing as his true and lawful
attorneys-in-fact and agents to:

               a. Execute for and on behalf of the undersigned such Forms 3, 4
                  and 5 ("Forms") as may be required from time to time by
                  Section 16 of the Securities Exchange Act of 1934 and the
                  applicable rules thereunder ("Act"); and

               b. Do and perform each and every act and thing for and on behalf
                  of the undersigned which may be necessary or desirable to
                  complete the execution and timely filing of such Forms as
                  undersigned may be required to file with the Securities and
                  Exchange Commission and any other authority.

         The undersigned grants said attorneys-in-fact and agents full power and
authority to act and perform on behalf of the undersigned all and every act and
thing whatsoever required to be done in the exercise of the rights and powers
granted herein, as fully to all intents and purposes as said attorneys-in fact
and agents might or could do in person, with full power of substitution or
revocation, hereby ratifying and confirming all that such attorneys-in-fact and
agents, or their substitutes, may lawfully do or cause to be done by virtue
hereof. The undersigned hereby acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming any of the undersigned's responsibilities to
comply with Section 16 of the Act.

IN WITNESS WHEREOF, the undersigned has executed this Power of Attorney this
16th day of March, 2005.


                                              ---------------------------------
                                                 Joseph M. Zubretsk{