Generation of the floxed Arf4 allele to characterize tamoxifen-induced deletion of <i>Arf4</i> postnatally.

<p>A. The mouse <i>Arf4</i> gene consists of six exons. The <i>Arf4</i>^<i>flox</i> mouse has LoxP sites flanking exons 2 and 3. Upon Cre recombinase expression, a frame shift is introduced after residue 22 causing early truncation of this 180 amino acid protein. The position of the early truncation site in relationship to the N-terminal functional regions of ARF4 is illustrated on the cartoon at the bottom of this panel. B. Tamoxifen was administered to <i>Arf4</i>^<i>flox</i><i>/CagCreER</i> mice by intraperitoneal injection on P2. Animals were genotyped at P10 where only 2/3 as many experimental mice were identified as expected (P = 0.0002 by Chi-square analysis). Orange and black dots represent weights of control and experimental mice at harvest. Curves are logarithmic best fits and are significantly different (P = 0.0003 by F test). C. At P91, Arf4 experimental mice are smaller in size and have grey coat color compared to littermate controls. Both experimental and control mice were black until 6–7 weeks of age when the experimental mice turned grey. Experimental mice were noticeably smaller and died at random times.