Figure 2: Localization of PARP-1 in a LNCaP spheroid and structure of a multicellular spheroid (MCS). (A) A section of a 7-day spheroid was stained with an anti-PARP-1 antibody (A6.4.12; Serotec, Oxford, UK). There is the intermediate zone with p27 immunostaining. (B) Structure of a MCS and characteristics of the tumor microenvironment. The structure of the spheroid favors genetic and epigenetic alterations.