Figure 3. Stable knockdown of endogenous ME2 levels in K562 cells results in apoptosis in vitro and suppresses tumor formation from K562 cells in vivo.

A: Knockdown of ME2 induces apoptosis in K562 as detected using the annexin V reagent. Data are expressed as mean ± SD, n = 3. B: Stable knockdown of ME2 in K562 cells failed to generate tumors in nude mice. Approximately 10⁷ ME2 deficient or control K562 cells resuspended in 200 µl of a serum-free culture medium/Matrigel mixture (1∶1) were subcutaneously implanted into female athymic nude mice as described under “Materials and Methods”. Tumor-bearing mice were sacrificed after 4 weeks and the mice photographed before excision and weighing. a, Left (L): pLKO; Right (R): shME2-2: b, L and R: shME2-3. Tumors formed only in the pLKO transduced cells.