在細胞移動過程當中，引導訊息分子經常利用濃度梯度的方式引導移動中的細胞，使其移動至正確的位置。在果蠅邊境細胞遷移過程中EGFR/PVR為其主要引導訊息並影響其移動方向。當rap1基因發生突變或是過量表現其持續活化態Rap1V12時會破壞原本其突觸的方向性進而影響細胞遷移。本篇研究透過基因篩選的方式找到可能參與此路徑的基因spen，其不同突變等位基因皆可使Rap1V12造成的移動不全成為正常移動。反之，過量表現Spen則會加劇其結果，使細胞更加無法移動。利用PZ spen果蠅發現spen轉錄於濾泡細胞及邊境細胞當中，顯示其可能在邊境細胞當中有功能。使邊境細胞中的spen不表現時，邊境細胞依然可以正常移動，顯示可能有其他未知路徑行使相同的功能。過去研究指出spen影響EGFR/PVR下游Yan的表現量，因此透過Yan在核中的表現量，本篇研究探討Rap1及Spen對訊息路徑EGFR/PVR的調控，並提出一種新的調控機制。

As preliminary data shows that rap1 mutant or over-expression (OE) of constitutively active or inactive Rap1 cause migration defect, this thesis screened for which gene specifically will interact with rap1 genetically by using RNAi or mutant lines of every single gene. split ends (spen) is found to suppress the migration defect phenotype. About 80 percent of the stage 10 egg chambers have the border cells normally migrate to oocyte boundary in the flies with different alleles of spen mutant with Rap1V12 OE, compared with 30 in Rap1V12 OE only. The spen over-expression, on the contrary, can enhance the migration defect caused by Rap1V12 OE. The spen PZ line shows the transcription pattern of spen is in follicle cells and border cells during oogenesis. The spen mosaic mutant clone specifically in border cell shows that spen mutant clone in the border cell do not affect the migration process, which means the spen might be redundant to other genes in regulation of border cell migration. Previously, Spen protein are suggested to regulate Yan, an EGFR downstream transcription factor. To know the role of spen in EGFR/PVR pathway, the EGFR/PVR downstream Yan protein were stained as a reporter for this guiding signaling pathway. The genetic interaction between spen, yan and Rap1 were studied in order to know their genetic relationship. Both yan mutant and over-expression of yan enhance the Rap1V12 caused migration defect. Previous paper shows that Yan expression and down-regulation is required for border cell migration. It means that Yan expression level is spatially controlled by EGFR/PVR signaling that possibly through Rap1 and spen.

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