I've been trying to obtain myosin light chains and troponin bands using a 12% SDS-Page gel & silver staining, and some negative bands are appearing ie bands that are lighter intensity than the background. The bands are appearing where I would expect them to be. Please does anybody know what might be causing this? One suggestion I've had is that it might be protein overload, but firstly I don't follow why the bands would appear whitish; and secondly, on 2 separate gels (run at different times), I obtain a dark band for troponin T (one of the myofibrillar proteins) and a white band with the same concentration (from the same eppendorf tube) on the other. Any clues would be much appreciated. Thanks.