CaMKII is involved in a variety of cellular processes, including cell growth or hypertrophy,51 and it has been proposed as a good candidate for HF treatments.21 We demonstrate that CaMKII in the close environment of the β2AR-LTCC complex plays a crucial role, which could be exacerbated in the Crest domains of MI cells, in which the pathologically active LTCC can be controlled by blocking CaMKII (Figure S4). Here, ADRB2 is linked to hydrops fetalis.