This strain is a conditional expression model of K-ras G12C, generated by introducing the G12C point mutation into the mouse Kras gene. Under normal conditions, the expression of K-ras G12C is blocked by an upstream loxP-Stop-loxP cassette. Expression is achieved only upon crossing with Cre mice, where Cre recombinase-mediated loxP site recombination removes the blocking sequence. This enables precise temporal and spatial control of K-ras G12C expression and tumorigenesis. By mating with tissue-specific Cre mice, this model can conditionally express K-ras G12C in specific tissues, making it a valuable tool for constructing cancer models in various tissues and organs. Homozygous LSL-K-ras G12C mice are nonviable.