SIK2 and neoplasm: Conversely, expression of a constitutive active isoform of SIK2 (sik2CA (Wehr et al., 2013)) in Ras/Src-activated cells (ras1G12V;csk−/−,sik2CA) was sufficient to promote Ras/Src-dependent tumor overgrowth even in a control diet (Figure 4A,B).