{Reference Type}: Journal Article {Title}: Engineering threshold-based selection systems. {Author}: Pedone KH;González-Pérez V;Leopold LE;Rasmussen NR;Der CJ;Cox AD;Ahmed S;Reiner DJ; {Journal}: G3 (Bethesda) {Volume}: 11 {Issue}: 9 {Year}: 09 2021 6 {Factor}: 3.542 {DOI}: 10.1093/g3journal/jkab234 {Abstract}: Using model organisms to identify novel therapeutic targets is frequently constrained by pre-existing genetic toolkits. To expedite positive selection for identification of novel downstream effectors, we engineered conditional expression of activated CED-10/Rac to disrupt Caenorhabditis elegans embryonic morphogenesis, titrated to 100% lethality. The strategy of engineering thresholds for positive selection using experimental animals was validated with pharmacological and genetic suppression and is generalizable to diverse molecular processes and experimental systems.