Fig. 2.

Analysis of metastases formation through transplant and circulating tumor cell (CTC) assays. a A piece of a green fluorescent protein (GFP)-labeled metastatic tumor (TMet; arrow) implanted into the abdomen of an adult host grows to fill up the entire abdomen of the host fly in just 13 days, rapidly killing the host. b, c TMets continue to grow during serial implants. In early implants small tumor colonies were seen distant to the abdomen (b, arrow), but by T10 TMets became more compact in size and localized in the abdomen (c). d, e Levels of luciferase activity were measured from the hemolymph extracted from individual flies. d The percentage of flies found with over 10 CTCs in their hemolymph, n = 59 (week 2), n = 80 (week 3), n = 108 (week 4). e The number of CTCs found in the hemolymph of individual flies, measured at 3 and 4 weeks after clone induction. The threshold of cells considered significant (10) is displayed by a dashed line. f Sagittal section from an Apc-Ras-Sna fly with a macrometastases in the thorax (1) and small doublets of GFP⁺ cells near the cuticle of the abdomen (2, arrow). Scale bars: (1) 50 µm and (2) 25 µm