During Drosophila oocyte production, initially spherical egg chambers elongate along the anteroposterior axis to create the fly's distinctive ovoid-shaped eggs. Multiple mechanisms have been implicated in egg chamber elongation, including the alignment of actin filaments and Collagen IV fibre-like structures in the follicle cells that surround the chamber. Follicle cell migration also leads to egg chamber rotation, which has been suggested to be essential for egg chamber elongation. These mechanisms rely on the action of Fat2, an atypical cadherin that interacts with the WAVE regulatory complex (WRC) to promote actin nucleation in the follicle cells. Fat2 has three WRC interacting receptor sequence (WIRS) motifs, but their function is unknown. Here, Christian Dahmann and colleagues use CRISPR/Cas9 to produce flies lacking these three WIRS motifs. They find that egg chamber elongation still occurs in the mutants, and that the alignment of actin filaments and Collagen IV fibre-like structures still takes place. However, the Collagen IV fibre-like structures are shortened in the mutants, and atomic force microscopy reveals that the stiffness of the egg chamber basement membrane is disrupted. Surprisingly, loss of the WIRS motifs also prevents egg chamber rotation from occurring, suggesting that rotation is not necessary for egg chamber elongation. Overall, this study provides insights into the role of the Fat2 WIRS motifs and demonstrates that the egg chamber's rotation can be decoupled from its elongation.