Antisense oligonucleotides specifically suppress JNK1/2 expression and retard apoptosis of HCD-57 cells in the absence of EPO. Antisense and control oligonucleotides for JNK1/2 were introduced into HCD-57 cells by lipofection as described in Materials and Methods. EPO starvation was started 44 hours after cell transfection. Expression levels of JNK1/2, p38 MAPK, and ERK1/2 were determined by Western blotting analyses 74 hours after EPO starvation (inset in the left panel). Apoptosis was determined by flow cytometric assays after 1 to 4 days of EPO withdrawal (left panel) and by fluorescent cell staining after 2 days (right panel). The photograph was taken with 400× magnification. Open bars and the top photo on right, EPO-containing medium; reverse-slashed bars and the second photo on right, EPO-free medium; horizontal bars and the third photo, EPO-free medium plus antisense oligonucleotide; and slashed bars and the bottom photo on right, EPO-free medium plus control oligonucleotide. Bright cell images indicate apoptosis.