GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE328nnn/GSE328830/primaryOK200OtherHomo sapiensOtherhttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE328830GEOGSEfalseTemporal control of sgRNA library activation unlocks large-scale in vivo CRISPR screensFunctional genomics screens have revealed cancer gene dependencies, but cell culture misses vulnerabilities driven by the tumor microenvironment. We implemented CRISPR-StAR (Stochastic Activation by Recombination), an inducible pooled screening system that activates gene knockout after tumor engraftment and provides matched internal controls for guide-level normalization. Using barcode-embedded sequencing and Bayesian analysis, we screened a 30,000-sgRNA library in A549 xenografts and achieved reproducible dropout and enrichment phenotypes using just ~30 tumors. Across additional xenograft models, single tumors yielded reliable functional annotation for ~1,000 genes leveraging within-tumor normalization. Comparing in vivo and in vitro screens uncovered tumor-suppressor effects detectable only in vivo; for example KMT2C and KMT2D knockouts produced contrasting tumor growth and transcriptional programs. Together with our R analysis package, CRISPR-StAR enables scalable in vivo dependency mapping that complements in vitro resources and reduces animal use up to sevenfold versus conventional dropout screens, improving overall methodological rigor at genome-scale clonal resolution.2026/04/29GSE328830GSM9690411GSM9690415GSM9690414GSM9690413GSM9690412GSM9690418GSM9690417GSM969041630173328830Homo sapiens