overlay gridded data on the worldmap

Dear users

i have 3 matrix that contain regional lat, long and data which i can plot using the pcolor command (h=pcolor,x,y,z). I want to overlay this data map on the worldmap provided by matlab (or any coastline and country borders data). I could not manage it so far. although i do not get any errors, the coastlines do not exist in the final product, but only my gridded data.

can you help me how to do this please?

thank you