Transgenic mouse cells expressing ts SV40 large T

Abstract

The provision of cell lines from virtually any cell type of the animal body is greatly facilitated by transgenic non-human eukaryotic animals of the invention in which at least some cells have (i) a differentiation inhibiting sequence chromosomally incorporated under the control of a non-constitutive promotor and/or (ii) a differentiation inhibiting sequence which is itself conditionally active. Said genes are chromosomally incorporated under the control of a promotor such that expression of said sequence is normally held below an effective level, thus allowing normal cell development. However, cells taken from said animal may be prevented from completing differentiation to a non-dividing state in tissue culture by activating expression of said sequence.

Dependencies are inferred from the claim text.