FRS2 is a potential target of miR‐339. (A) putative miR‐339 binding sites in the 3′ UTR of FRS2 along with the mutation sites. (B) 3′ UTR luciferase reporter constructs with wild‐type (WT) or mutant (MUT) sequence of FRS2 3′ UTR transfected with miR‐339 or control mimic. Bar charts of luciferase reporter analysis represent mean ± SE (n = 3), firefly luciferase activity was normalized to renilla luciferase activity, *P < 0.01, with Student's t test comparing indicated group, ns represents no significance. (C) RPASMC was transfected with miR‐339 or control mimic for 72 h, western blot was performed to determine the protein level of FRS2, β‐actin was used as endogenous control, n = 3. (D) RPASMC transfected with si‐FRS2 or control siRNA for 72 h, western blot was performed to determine the protein level of FRS2, β‐actin was used as endogenous control, n = 3. (E) Bar charts showing relative EdU incorporation rate in RPASMC transfected with si‐FRS2 or control siRNA for 72 h, n = 4, #P < 0.05 versus control siRNA.