Up Checks & Bosses

I have a question - the Highway Ronin has this ability - "Against all Warlords - Add +2 Guns vs. Bosses. if the boss succeeds at an Up Check, you can force the GM to reroll the Up check. Up or down, use the second result". I thought only Heroes made Up checks. According to the rules on page 105, "At 50 or more Wound Points, the GM rolls a single die. On an odd result, the boss keels over. On an even result, the boss keeps fighting." Is this even/odd roll on a d6 concerned the Bosses Up Check?

There are a few schticks that refer to Bosses making Up Checks so a clarification would be good


Yep, the even/odd check that a boss makes when they're over 50 Wound Points would be their Up Check.