p can be embedded in a super-reflexive space X so that there is an operator $T\dvtx\ell_{p}\to\mathcal{C}(K)$ which has no extension, answering a question of Zippin.
@article{1242414132,
author = {Kalton, N. J.},
title = {Automorphisms of $\mathcal{C}(K)$ -spaces and extension of linear operators},
journal = {Illinois J. Math.},
volume = {52},
number = {1},
year = {2008},
pages = { 279-317},
language = {en},
url = {http://dml.mathdoc.fr/item/1242414132}
}
Kalton, N. J. Automorphisms of $\mathcal{C}(K)$ -spaces and extension of linear operators. Illinois J. Math., Tome 52 (2008) no. 1, pp. 279-317. http://gdmltest.u-ga.fr/item/1242414132/