Fig. 2.

Adenosine receptor A3 is expressed in normal and osteoarthritic articular cartilage. a Protein expression of A3 was detected in the superficial and transitional layer of healthy human articular cartilage. Control sections were stained with secondary antibody only. Images in the lower panels represent a higher magnification view of areas marked in the corresponding upper panels. b Expression of A3 reduced in OA adult cartilage is characterized by progressive loss of the superficial chondrocytes. N = 5 independent donors from both healthy and OA articular cartilage from the knee joint. P values were calculated using Student’s t test (two-tailed). P values < 0.05 were considered to be significant. Scale bar = 20 μM. Representative images are shown. Detailed information about donors can be found in the “Materials and methods” section