Fig. 4. Effect of LIF deficiency in early mammary gland development. (A) Whole-mount staining of mammary glands from pregnancy day 8 Lif^-;/-; (1,3,5) and Lif^+/-; (2,4,6) mice at three magnifications. (B) ERK, STAT5 and STAT3 activation in early development. Glands from pregnancy day 8 Lif^-;/-; and Lif^+/-; control mice were subjected to western blot analysis using specific antibodies against pSTAT3, total STAT3, pSTAT5, total STAT5, pERK1/2 and the epithelial marker protein Cytokeratin 18 (Ker18). Graphs indicates densitometry analysis for three independent mice, mean±s.e.m. Lif^-;/-;, black bars; Lif^+/-;, white bars. (C) Whole-mount staining of mammary glands from Lif knockout (1,3) and control Lif heterozygous (2,4) virgin animals. Whole-mount staining of the glands from 4-week-old virgin mice (1,2), and 7-week-old virgin mice (3,4).