Hi Jens, 

Thanks for your reply.

I am using GFP-actin to track these podosomes. Im not sure whether I should 
use a labelling kit or a commercially available labelled actin which which is far 
smaller than GFP! I will be trying this.

Im wondering what software you use for auto tracking?

Furthermore, would you be able to send one of your videos? Id like to see 
what your structures look like on TIRF. Of course, I understand that you may 
not be able to share your videos which is fine!

regards