(A) GASC1 knockdown of Tf–PEI with siRNA sequence V7 shows that the conjugate was able to knock down mRNA levels of GASC1 more efficiently than the commercially available siRNA sequences in HCC1954 cells. V4, V6, and V7 are self-designed GASC1 siRNA sequences. NC = scrambled siRNA; PC = positive control siRNA (hGAPDH), error bars reflect SD, n = 3; ns, nonsignificant; *P < 0.05, **P < 0.01, ***P < 0.001, and ****p < 0.0001. (B) GASC1 protein knockdown in HCC1954 cells with Tf–PEI compared to PEI alone was confirmed by Western blot. Alpha-tubulin was used as the loading control. Top row: A, PEI/V7GASC1 siRNA; B, PEI/NC siRNA; C, Tf–PEI/V7GASC1; D, Tf–PEI/NC siRNA.