What is the fine-grained topic of the following text: Using specific methods to prepare cartilage extracts and conditioned media for 2-dimensional polyacrylamide gel electrophoresis and subsequent tandem mass spectrometry, we identified novel proteins and fragments released into the media of control, interleukin-1alpha (IL-1alpha)-treated, and all-trans-retinoic acid (RetA)-treated explants. Only return the topic.
Identification of proteins and fragments in cartilage extracts using gel electrophoresis and tandem mass spectrometry.