Effect of KB-R7943 on SiHa spheroids. SiHa spheroids were grown either in normal environment (No), or in the presence of KB-R7943 (KBR). Representative images of these spheroids at the day 8 and 10 are shown (A). After the day 10, spheroids were subjected to Western blot analysis, which proved the presence of CA IX, NCX1 and HIF-1α protein (B). In the presence of KB-R7943, SiHa spheroids disintegrated rapidly compared to untreated spheroids. Size of the spheroids at the day 8 and 10 is shown in the graph (C). Results are displayed as mean ± S.E.M., n = 15. Statistical significance *—represents p < 0.05 compared to control. (C). Number of apoptotic cells (D, striped columns) decreased in 8 and 10 days spheroids due to KB-R7943 treatment, while number of necrotic cells significantly increased (D, black columns). Empty columns represent number of alive cells in 8 and 10 days spheroids (D).