Double labeling of nuclear antigens and microtubules. Fixed and BSA-
blocked 3T3 cells were incubated sequentially with a mixture of ANA and
mouse anti-α-tubulin overnight at 4 3 biotinylated anti-human
IgG and 40 nM red QD 630–streptavidin for 30 min each. The cells then
were blocked with 50 biotin for 20 min, rinsed, and incubated sequentially with 15 biotinylated anti-mouse IgG and 40 nM green QD
535–streptavidin for 30 min each.