| No PKC beta ( 2 ) complexes with lamin B 1 and / or active caspases were immunoprecipitable from the NM of proliferating untreated cells , but large complexes of PKC beta ( 2 ) holoprotein and its catalytic fragments with lamin B 1 , active caspase 3 and 6 , and inactive phospho CDK 1 , but not PKC beta ( 1 ) or PKC delta , could be immunoprecipitated from the NM of VP 16 treated cells , suggesting that PKC beta ( 2 ) is an apoptotic lamin kinase . ^^^ By 30 min after normal nuclei were mixed with cytoplasms from VP 16 treated , but not untreated , cells , PKC beta ( 2 ) holoprotein had moved from the apoptotic cytoplasm to the normal NM , and lamin B 1 was phosphorylated before cleavage by caspase 6 . ^^^ Thus , a PKC beta ( 2 ) response to VP 16 seems necessary for lamin B 1 cleavage by caspase 6 and nuclear lamina dissolution in apoptosing pyF 111 fibroblasts . ^^^ The possibility of PKC beta ( 2 ) being an apoptotic lamin kinase in these cells was further suggested by lamin B 1 bound PKC delta being inactive or only slightly active and by PKC alpha not combining with the lamin . . ^^^ |