A method and apparatus in a base station serving a first cell in a cellular network, for supporting radio resource management, RRM, in the cellular network. The base station obtains measurements (M) of signals transmitted in the first cell and of signals transmitted in at least one neighbouring cell and determines a cell isolation factor of the first cell, based on the obtained measurements, the cell isolation factor indicating insusceptibility to interference from signals transmitted in the neighbouring cell(s). The determined cell isolation factor is then used to support RRM for terminals in the network, e.g. as a basis for determining whether to employ an RRM scheme or not. Thereby, it is possible to decide to employ the RRM scheme for cells where it is effective and helpful and not in other cells.