Human growth differentiation factor-9 (GDF9) is expressed almost exclusively by oocytes, but is secreted in a latent form. Recent studies have indicated that human GDF9 is activated by forming a heterodimer (called cumulin) with the closely related molecule bone morphogenetic protein-15 (BMP15). Cumulin added to in vitro maturation (IVM) media of immature porcine or human oocytes markedly increases subsequent embryo yield, identifying this molecule as an attractive therapy for the treatment of female infertility. However, the heterodimeric nature of cumulin makes mass production difficult and prone to batch-to-batch variability in potency. To address this, we sought to generate an engineered form of GDF9 with ‘cumulin-like’ ability to activate the Smad-2/3 transcription pathway. BMP15 residues (Arg363, Gly366, His369), predicted to activate GDF9 within the cumulin heterodimer, were introduced into the GDF9 homodimer. Collectively, the introduced mutations were non-disruptive for GDF9 assembly and secretion. Excitingly, the modified GDF9 form was capable of inducing Smad-2/3 activity in human granulosa COV434 cells, with greater potency than cumulin. Replacement experiments indicated that all three residues are required for maximal activation of the Smad-2/3 pathway. Ongoing studies will determine if, like cumulin, our modified GDF9 can improve oocyte quality and blastocyst production.