Currently I am trying to read and understand this paper on intein splicing. https://sci-hub.tw/https://www.ncbi.nlm.nih.gov/pubmed/22001202
However, I'm a little confused with Figure 4.
Why do the authors have Fig. 4a and 4b, but it is not talked/referenced about anywhere in the paper?
"temperature does not visibly affect the splicing of highly efficient inteins"
Is that a reference to 4a? Furthermore, why is temperature important for some inteins but not for others? Why is this significant?