Whether ventricular cardiac myocytes of mouse contain caveolin-1 is disputed. It has been claimed to be exclusively in nearby endothelial cell profiles. Recently, matrix metalloproteinase-2 (MMP-2) was reported to be present in mouse ventricular cardiac myocytes, colocalized with caveolin-1, and caveolin-1 knockout was found to cause the loss of MMP-2 from mouse ventricular cardiac myocytes and affect their functioning. To resolve this dispute, we labeled cardiac myocytes with caveolin-1 and endothelial cells with caveolin-2. Caveolin-2 is agreed to be present exclusively in endothelial cells. The results showed that mouse ventricular myocytes were labeled with caveolin-1 antibodies independently of any caveolin-2 labeling, and endothelial cells were labeled with both caveolin-1 and caveolin-2 antibodies. This confirms that caveolin-1 is present in mouse ventricular cardiac myocytes as well as endothelial cells. Previous evidence confirms that loss of caveolin-1 affects the function of mouse ventricular cardiac myocytes and suggests that MMP-2 may be involved.