Abstract: Provided herein are methods and compositions for detection and quantification of one or multiple target miRNA(s) in biological fluids and/or tissue samples using alternating laser excitation (ALEX) single molecule fluorescence spectroscopy, and employing such methods and compositions for diagnostic, prognostic, therapeutic, and/or research applications.

Abstract: Non-human mammals comprising a disrupted MSH2 gene are disclosed. More particularly, animals having a disruption in one or both alleles of the MSH2 gene or a homolog of the MSH2 gene are disclosed. Animals homozygous for the disruption are viable past the embryonic stage of development but show an increased incidence of lymphoma, intestinal adenomas and carcinomas, and squamous cell tumors of the skin. Specifically disclosed are mice whose genome comprises a disrupted MSH2 gene such that the mice exhibits an increase in the incidence of spontaneous lymphoma over the incidence of spontaneous lymphoma in wild type mice.