RenderToCubemap with Image effect?

Hello again!

Is there any way to make a camera enable RenderToCubemap function with Image effect?

These are I've tried.

1. I made a cubemap rendertexture without image effect and cast it to a texture2d. but i couldnt make texture2d blur and copy back to cubemap rendertexture.

2. I imported standard image effects to bring in the BlurEffect script. So make my own script with copy of function OnRanderImage. the function itself have Graphics.Blit call, I have expected it would have work. Bot didnt. - It looks like unity cant RenderToCubemap while Graphics.Blit.

Is there any suggestion?