I decided recently to apply to MSTP programs this cycle and I realized that although I will have 4 great letters of recommendation from labs that I've worked in and doctors that I have shadowed, I have not established any relationship with course professors. And I know that most MSTP programs require letters from 2 science course professors and 1 non-science professor. Now I am scrambling to make connections with my course professors. I was wondering how important letters from course professors are and whether really strong letters from PIs and doctors would balance out potentially less than stunning letters from course professors. My logic is that this is the case since MSTP cares more about talent and commitment in research than in coursework but I may be wrong.