These transgenic mice express the eGFPCreERT2 (Enhanced Green Fluorescent Protein and cre/ESR1) fusion gene under the direction of the mouse S100b, S100 protein, beta polypeptide, neural, promoter. Transgene expression is detected in chondrocytes in developing bone and in neural cells in the dorsal root ganglia (DRG). GFP fluorescence is not detectable by fluorescent microscope examination of whole embryos, bones or neural tube sagittal slices from embryos aged 15.5dpc. Tamoxifen induced Cre recombinase activity is detected in a subset of the GFP immunoreactive-positive cells in bone and to a lesser extent in the dorsal root ganglia. GFP immunoreactive-positive cells co-localize with S100b immunoreactive-positive cells in bone and DRG. Other possible sites of expression have not been characterized. Mice that are hemizygous for the transgene are viable, fertile, normal in size and do not display physical or behavioral abnormalities. The Jackson Laboratory 2024, used with permission.