Horns reads are the same.
If X1 chases over the screen, O1 turns the corner and drives hard to the basket.
If X2 sags off to help out, O1 makes a kick-out pass to O2 spotting up.
If X4 drops off to help out, O1 makes a drop pass to O4 (rebound/drop pass zone).
Under the screen
When X1 goes under the screen (and X5), O1 pulls up for a shot.
(Lionel Hollins, FIBA Assist, issue 5 - the player stops and takes a jump shot.)
Show and recover
Post roll - When X5 shows against the screen, O1 strings out X5 with the dribble and O5 rolls to the basket looking for a pass. If X4 moves across to guard O5, then O5 pops and O4 cuts to the basket.
Post pop - When O5 is a good outside shooter, O5 has the option of popping out instead of rolling to the basket. If O5 pops O4 goes opposite and dives to the basket. Defender X5 will have a hard time recovering against O5.
If X5 is in foul trouble, O1 should drive hard to the basket looking to draw a foul..
(Lionel Hollins - If the defence forces the ballhandler outside he passes to the screener who rolls. Hollins shows an early pass to a screener near the weakside elbow.)
O1 immediately strings out (spreads) the double team with the dribble.
Post roll - 05 rolls to basket, O1 can pass directly to O5 or to any of the peripheral players to feed O5. The ball must be moved in the air against the trap with sharp passes (no dribbling).
Post pop - When X4 moves across to guard O5, O5 pops out and O4 cuts to the basket. O1 can pass directly to O4 or to any of the peripheral players to feed O4.
(Lionel Hollins - The offence has to spread the defence, by passing to the open player as soon as possible. The screener may want to slip the screen early to provide an outlet, forcing a rotation then finding the open teammate.)
Post roll - When X1 and X5 switch, O1 looks to feed screener O5 rolling to the basket or posting up against the smaller defensive guard.
Post isolation - When O5 has a mismatch advantage against smaller X1, O5 posts up looking for a feed from any of the peripheral players.
Post slip - When X1 and X5 anticipate the switch and zone (without coming together), O5 should fake the screen and slip (cut away) to the basket.
Since the midscreen involves a big screening for a small, most NBA teams do not like to switch. If the defence switches, the dribbler will simply flare to the wing allowing the screener to slide down and post up against the smaller defender.
Point isolation - When O1 has a definite advantage over bigger X5, screener O5 clears out allowing O1 to go one on one against X5.
O1 can make a kick-out pass to O2 if X2 drops off to help, or a drop pass to O5 if X1 helps.
If O1's shot is not available, O5 can dive to the basket to exploit smaller X1.