Some proteins, mostly Glycoproteins, show a special behavior in electrophoresis. In the case they are strong concentrated the bands are wavy shaped.
Glycoproteins are partly build out of sugar. SDS will not bind to this part of the molecule.
This causes striking bands because the starting process is too quick for them.
Remedy is to perform a slow start of the electrophoresis (mA and W minus 50% in phase #1).
Also addition of Boric acid (250 mM) to the sample buffer can help by charging the sugar of Glycoproteins nagatively.