Here's yet another article arguing for Central European genetic influence in East Slavs. The question is, does this influence include the spread of the proto-Slavs from Poland to the east, or later movements of West Slavs from Poland or even Germany to Belarus and Ukraine, or both?
We have tested a sample of 154 unrelated males from Lviv region (Ukraine) for 11 Y-chromosomal single nucleotide polymorphisms (SNPs) and 17 Y-chromosomal STR loci (DYS19, DYS385a, DYS385b, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, YGATA_H4.1). Haplotype and haplogroup diversity values were calculated for the population under study. Genetic distances (RST) to 9 other Slavic populations were calculated based on 12 Y-STR loci. Haplotype frequencies and MDS plots were constructed based on genetic distances. Haplogroup frequency patterns revealed in Ukraine are similar to those characteristic of other European populations. However, it also allowed for identification a specific genetic component in Ukrainian sample which seems to originate from areas dwelled by Western Slavs, i.e. subhaplogroup R1a1a7, at frequency of 13.65%. Analysis of RST distances and AMOVA revealed high level of heterogeneity between Slavic populations inhabiting the south and north part of Europe, determined geographically rather than by linguistic factors. It has also been found a closer similarity (in the values of RST) between Ukrainian and Slovak populations than between Ukrainians and other Slavic population samples.
Mielnik-Sikorska et al., Genetic data from Y chromosome STR and SNP loci in Ukrainian population, Forensic Science International: Genetics, Volume 7, Issue 1 , Pages 200-203, January 2013, http://dx.doi.org/10.1016/j.fsigen.2012.05.007
Belarusian R-M458 and the Polabian connection
The history of slavs in the light of Y chromosome and mtDNA variability
Russian mtDNA, Goths of the Ukrainian steppe, and a proto-Slavic expansion from present-day Poland (Morozova et al. 2011)