MAPK1 and Merkel cell skin cancer: Interestingly, PARP1 and PHB2 have also been previously shown to directly or indirectly interact with and/or regulate MCC targets identified by knockdown and overexpression of MCC studies in human MM cells (Figure 6), including ERK, c-Myc, p27, cyclin B1, Mcl-1, caspase 8, and caspase 3 [62–65].