bcl-2 molecular mass

[ADRIAN JORDAAN PUREN]

We have been doing Western blots to detect bcl-2 expression in HL-60 cells 
following incubation with various stimuli. Proteins were electrophoresed 
on 15% SDS-PAGE. We have identified a major molecular mass species (28 
kDa) but in addition have observed the presence of two lower molecular mass 
species (24-26 kDa). The presence of the latter depend on the nature of the 
stimuli and are thought not to be degredation products and also not non-
specific. A mononuclear cell control shows the major molecular 
species only. Has anyone else come across this phenomenon (practically or in 
the literature)? We would appreciate comments.