Figure 1: rhTNF-α Increases Apoptosis in OA Chondrocytes. rhTNF-α (10 ng/ml to 50 ng/ml) was incubated with OA chondrocytes for 48 hrs. Intranucleosomal DNA fragments were identified using the manufacturer’s protocol as previously modified by Islam et al. [23]. DNA electrophoresed on a 1.2% agarose gel, stained with ethidium bromide (EtBr) and DNA fragments visualized using a Vilber-Laurmat UV Illuminator [23]. The lane marked DNA Ladder (supplied by the manufacturer) shows the migration of EtBr-positive bands characteristic of intranucleosomal DNA fragments from apoptotic cells. Lane 1: No addition; Lane 2: rhTNF-α (10 ng/ml); Lane 3: rhTNF-α (20 ng/ml); Lane 4: rhTNF-α (50 ng/ml). Note the 2 DNA fragments indicated by the arrows which showed increased EtBr signal intensity as a function of rhTNF-α concentration.