Figure 1. Hypoxia endows Hs294T and A375 melanoma cells with stem-like traits.

(A, B) Starved Hs294T (left) and A375 (right) cells were cultured under normoxic (21% O₂) or hypoxic conditions (1% O₂) for 24 h in the presence or absence of Etoposide (50 μM). Serum deprived cells in normoxic conditions (21% O₂) were used as control. P0 (primary) and P1 (secondary) melanospheres were obtained from the above treated cells. Photographs of P0 spheres were taken and shown (above the corresponding treatment), while P1 spheres were counted and plotted. (C) Starved Hs294T and A375 cells cultured under normoxic or hypoxic condition for 24 hours and treated or not with Etoposide (50 μM). were analyzed for CD133 staining. (D, E) Cells disaggregated from P0 spheres derived from Hs294T (left) and A375 (right) cultured under normoxic or hypoxic conditions treated or not with Etoposide (50 μM). were analyzed for CD133 staining. P values of ≤ 0.05 were considered statistically significant *p < 0.05, **p < 0.001, ***p < 0.0001, n = 3.