PCNA and neoplasm: Regarding the effect of the treatment on PCNA expression, the impact of VPA–NaDCA on the T98G tumor on the CAM is characterized by a synergistic effect of the combination components: the frequency of PCNA-positive cells was lowered considerably in those treated with 50 μM TMZ or VPA–NaDCA tumors, while 3 mM NaDCA did not affect PCNA expression in T98G tumors.