ref-1 is expressed in specific subsets of E lineage cells and in other cells in the embryo. We found strong reporter expression in Eal and Epl cells but also weak reporter expression in both right daughters of Ex cells, with the level of expression correlated with the proximity of the cells to the MSapp cells. In wild type embryos Epl is further from the MSapp cell than Eal, and has a significantly lower level of
ref-1 reporter expression (p-value = 6.2e-5). In addition Ear and Epr are yet more distant from MSapp and have still lower expression. Plotting
ref-1 reporter expression versus distance from MSapp produces a high negative correlation.