|| Fosl1 protein was mutated and truncated to generate 3 mutant polypeptides which then cloned into pcDNA3.1 plasmid (pcDNA-Fosl1-NT, pcDNA-Fosl1∆DB, and pcDNA-Fosl1∆LZ ). Full length of Fos, FosB, and Fosl2 were amplified from X. tropicalis cDNA library and cloned into pcDNA3 plasmid to construct pcDNA-Fos, pcDNA-FosB, and pcDNA-Fosl2 plasmids. Fosl1-NT with the maximum capacity to inhibit Fosl1-driven luciferase activity was used as the dnFosl1 due to its safety for other Fos proteins The DNA fragment of dnFosl1 was then fused with a T2A-EGFP coding sequence and cloned into a I-SceI transgenesis vector downstream of the 3 kb mlc2 promoter to construct the transgenesis plasmid pMlc2-dnFosl1-T2A-EGFP. The transgenesis plasmid and I-Sce1 enzyme were then injected into the animal pole of X. tropicalis embryos at one-cell stage to generate a transgenic line. Founder X. tropicalis were identified and propagated to establish this stable line.