Figure 1. Slit/Robo2 signaling between enteroendocrine and stem/progenitor cells in the posterior midgut.

(A,B) The Slit promoter is active in EEs, as shown by the detection of β-galactosidase in prospero-positive cells, using the Slit^PZ05248-LacZ reporter line (A; arrowheads), and inactive in escargot-positive progenitors and polyploid enterocytes (B).

(C,D) The Slit protein is detected in the cytoplasm of prospero-GFP-positive cells (C; arrowheads, and see Supplementary Fig. 2b for the characterization of the pros-GFP reporter) and at the periphery of escargot-positive cells (D; asterisks).

(E) The Robo2 receptor is expressed in esg-positive cells, as shown by immunocytochemistry using a Robo2-specific antibody.

(F) Knock-down of lea/Robo2 in esg-positive cells is sufficient to abolish the accumulation of Slit at the surface of these cells (asterisks) without affecting Slit expression in EEs (arrowheads). Over-expressing Robo2, using the lea^EP line, increases the signal at the periphery of ISCs.

(G) Quantification of Slit immunostaining intensity in esg-positive ISCs/EBs compared to esg-negative diploid EEs in similar conditions as Figure 1F.

n represents the number of pairs of diploid cells (one esg-positive and one esg-negative) that were analyzed. p-value from two-tailed Student's t-test. See also Figure S1.