Inverted U-shape and moderation

Good afternoon,

I'm working with panel data, a fixed effects model, and I'm testing an inverted U-shape between my main independent variable (X) and the dependent one (Y). Thus, I have included X (which is positive and significant) and X^2 (which is negative and significant) in the regression.

The thing is now I want to test how a moderator "M" affects the relation between X-->Y. Thus, I have also included the interaction terms "X*M" and "X^2*M". My questions are:

1. The coefficients for X*M and X^2*M are significant in my model, but X and X^2 are not significant anymore. Can we confirm M is moderating the inverted U-shape?
2. How can I plot this in STATA?

I'm sure these are basic questions, but I'm a beginner... Thanks a lot for your help!