MYC and Familial prostate cancer: Phosphorylation of GSK3-β on the S9 residue inhibits its kinase activity, knockdown of HN1 in prostate cancer cells PC-3 and LNCaP inhibits pGSK-3β(S9) [10], we concluded that HN1 could increase the stability of MYC by suppressing the kinase activity of GSK-3β.