Antibody should be further diluted ( used at 1/400)

Cells were both scraped or trypsinised ( in case enzyme altered signal), spun down. Resuspended in 10 % Formalin O/N at RT.

Spun down, rinsed/resuspended  in TBS.

After another spin, cell pellet was resuspended in HMP Agarose at 50C and then immediately spun down at 4K for 5 mins.

Agarose gel containing pellet was processed to Pwax conventionally.

Is this positivity specific?

It appears to be identical to that seen using ab40815 and also ab52894

Sure, one sees membrane positivity.