HIF1A and neoplasm: Both these cell lines lack HIF-1α expression.19 Five additional ccRCC cell lines (SKRC7, SKRC10, SKRC17, SKRC21 and SKRC52), commonly used to study this tumor type in vitro, were included in these studies, in order to determine whether also other ccRCC cell lines were equally resistant to 3BrPA, and also to ensure that the lack of HIF-1α was not a determining factor in the resistance of the established cell lines to 3BrPA treatment.