Why is my loading control giving me so many bands (western blot)?

I ran an SDS-PAGE today to test 4 different loading controls: tubulin, actin, GAPDH1, and GAPDH4. The tubulin and actin didn't even show up, but both of the GAPDH's showed up in several bands. There were so many bands both of them looked like they could be ladders. I did accidently boil the samples for an excess of 10 minutes, could this cause the proteins to degrade enough to create so many bands? If not, what could have gone wrong?