Correlation between the induction of TGase II protein and apoptosis in RPMI 8226 cells. Cells were incubated for 6 days in the absence of retinoids (A) or in the presence of 10⁻⁷ mol/LatRA (B) or the combination of both 10⁻⁷ mol/L CD367 and 10⁻⁷ mol/L CD2425 (C). TGase II protein expression was detected by indirect immunofluorescence using a monoclonal anti-TGase II antibody (left panel), and apoptotic cells were detected after MGG coloration on cytospin preparations (right panel).