a, Representative IF images of aPKCλ, COL17A1, CDC42, NUMB and PARD3 in HaCaT cells. Arrows indicates the co-localization between COL17A1 and cell polarity-related proteins. b, IF images of COL17A1 and PARD3 in si Cont (control) and in COL17A1 siRNA transduced NHEKs at 72 hr. c, IF images of PARD3, F-actin, NUMB and Plectin in si Cont (control) and in ITGA6 siRNA transduced NHEKs at 72 hr. KD of COL17A1 or ITGA6 decreased the polarized localization of cell polarity-related proteins in NHEKs (b, c). d, e, Quantitative RT-PCR analysis of mRNA expression levels of COL17A1 (d) and aPKCλ (e) in HaCaT cells at 96 hr after transfection of the indicated siRNA. f, g, Western blot hybridization analysis of COL17A1, aPKCλ, NUMB and TUBULIN in sh SCR or sh COL17A1 expressing stable HaCaT cell lines (f) or in HaCaT cells at 72 hr after transfection with si Cont or COL17A1 siRNA or pCMV-COL17A1 (g). h, j, IF images of COL17A1, aPKCλ, PARD3, NUMB and CDC42 in pCMV-COL17A1 transduced HaCaT cells (h) and NHEKs (j). i, k, IF images of ITGA6 and NUMB or aPKCλ in ITGA6-GFP over-expressing HaCaT cells (i) and NHEKs (k). OE of COL17A1 or ITGA6 provoked the increased expression of cell polarity-related proteins in the cortical region in HaCaT cells and in NHEKs (h, i, j, k). l, Immunoprecipitation analysis of the interaction between COL17A1 and aPKCλ in NHEK lysates. m, Immunoprecipitation analysis of the interaction between COL17A1 and aPKCλ in HaCaT cell lysates. Error bars, means ± SD; one-way ANOVA with Holm Sidak post-hoc test (d, e).