Furthermore, double-immunofluorescence staining with LTL (green) and cleaved caspase-3 and the corresponding quantitative data confirmed that metformin treatment induced marked apoptosis of the LTL-positive renal proximal tubular epithelial cells, with some apoptotic cells having sloughed off the basement membrane and fragmented within the lumen, resulting in shrunken renal cysts (Fig. 5f). This evidence concerns the gene CASP3 and Renal cyst.