JAK2 and neoplasm: Further detection of the expression levels of CDC5L and PEAK1 proteins and the activities of the ERK1/2 and JAK2 signaling pathways in xenograft tumor tissues using western blot showed that the expression levels of CDC5L, PEAK1, p‐ERK1/2, and p‐JAK2 were lowest in the circ‐PGAM1 silencing combined with miR‐542‐3p overexpression group (Figure 8C).