Figure 4. Lineage tracing of Apln⁺ cells in organs and tumours.

(a) Strategy of tumour implantation and tamoxifen treatment on Apln-CreER;Rosa26^RFP/+ mice. Tumours were retrieved at 10 to 15 days after implantation with obvious growth in size and processed for quantification of Apln-labelled vessels. (b) Whole mount pictures of organs or tissues from Apln-CreER;Rosa26^RFP/+ host mouse. (c) Whole mount pictures of implanted tumour (black dotted line) within host tissue. Magnified figures showed Apln-labelled tumour vessels. Asterisk indicates necrotic region inside tumour devoid of blood vessel. (d) Staining of genetic marker RFP and vascular EC marker PECAM, and smooth muscle marker α-smooth muscle actin (aSMA) on sections of the heart, brain, aorta and tumour tissue. (e) Quantification of RFP⁺ cells in PECAM⁺ vascular ECs of different organs and tumours. Values are shown as means±s.e.m.; n=3–5. Scale bars, 1 mm (b,c); 100 μm (d).