Methods are provided in a first radio network node for supporting transmission power adjustment of a mobile terminal and in a second radio network node for assisting the first radio network node in supporting such adjustment. The first radio network node and the mobile terminal are adapted to operate on a first radio access technology. The power adjustment of the mobile terminal is performed in order to reduce interference, caused by the mobile terminal, on the second radio network node. The second radio network node is adapted to operate on a second radio access technology. The method includes obtaining an indication that the second radio network node is interfered by transmissions from the mobile terminal, obtaining values of power control parameters for adjusting the transmission power of the mobile terminal and transmitting the obtained power control parameter values to the mobile terminal, in order to enable the adjustment of the transmission power of the mobile terminal. Related arrangements are also provided herein.