Frame and panel doors in MDF

[mseries]

I am going to have to build some frame and panel doors for a cupboard. Each door is about 15" x 40" and the frame will be 18mm MDF with 6mm panel. Please excuse my mix of imperial and metric dimensions, I am quite happy working with both. Anyway, do people bother with long tenons in the rails to join them to the stiles by means of a deep mortice ? or just rely on the short tenon that fills the groove made for the panel ?

 

[oakfield]

Just the stub tenons will be fine. As its all MDF, you can glue the panel in which greatly adds to the strength.
You could also use loose tenons and use off cuts from the panel material as the loose tenons.