Wigan and Brentford have both been linked with the midfielder in the past week.
The interest from Wigan was an enquiry to take him on loan – which was quickly brushed aside by PNE.
Brentford were linked with Johnson in the media but there is yet to be contact from the Bees, if indeed they are interested.
Preston are not actively looking to sell the 26-year-old but every player has a price, in his case probably something around the £2m mark.
Johnson was an unused substitute in the opening-day defeat at Millwall.
Paul Gallagher got the nod ahead of him in midfield but there was a switch in system from PNE boss Alex Neil, with him fielding a 4-1-4-1 instead of the 4-2-3-1 used for most of the pre-season.
Gallagher played a wider role on the left, leaving Ben Pearson as the deep-sitting midfielder.
Further competition in the midfield has come in the shape of Tom Bayliss. The 20-year-old signed from Coventry last Friday and will be in contention to face Wigan this weekend.
Neil rates Johnson highly, playing him in 38 games last season. Asked last week about Wigan’s interest in taking him on loan, Neil described the loan enquiry as ‘silly’.
You could see his point, the Lilywhites unlikely to let him out on loan to a club in the same division – if they really want him, pay cash.
Johnson has two years left on his contract having signed a new deal 12 months ago.
It remains to be seen what further business PNE do before the deadline, both in and out.
When it comes to outgoings, it must be remembered that sales and outgoing loans can still be done with clubs in League One and Two until September 2.
All incomings have to be completed by Thursday at 5pm.
North End saw a bid for Derby County left-back Max Lowe turned down the Rams last week.
It is unlikely that as things stand they will be go back in for 22-year-old Lowe who spent last season on loan in Scotland with Aberdeen.
Left-back cover is needed after Josh Earl was allowed to join Bolton on loan.
Earl, 20, suffered ankle ligament damage on his Bolton debut at Wycombe.