We present the isospin- and angular-momentum-projected nuclear density
functional theory (DFT) and its applications to the isospin-breaking
corrections to the superallowed beta-decay rates in the vicinity of the N=Z
line. A preliminary value obtained for the Cabbibo-Kobayashi-Maskawa matrix
element, |V_{ud}|=0.97463(24), agrees well with the recent estimate by Towner
and Hardy [Phys. Rev. C{\bf 77}, 025501 (2008)]. We also discuss new
opportunities to study the symmetry energy by using the isospin-projected DFT.Comment: Presented at the 17th Nuclear Physics Conference "Maria & Pierre
Curie" on "Symmetry and symmetry breaking in nuclear physics", Kazimierz
Dolny, 22-25 September, 2010, Polan